Bioenergy systems for the future 4 light olefins bio gasoline production from biomass

Bioenergy systems for the future 4 light olefins bio gasoline production from biomass Bioenergy systems for the future 4 light olefins bio gasoline production from biomass Bioenergy systems for the future 4 light olefins bio gasoline production from biomass Bioenergy systems for the future 4 light olefins bio gasoline production from biomass Bioenergy systems for the future 4 light olefins bio gasoline production from biomass

Light olefins/bio-gasoline

production from biomass

A Bakhtyari, M.A Makarem, M.R Rahimpour

Shiraz University, Shiraz, Iran

DME dimethyl ether

FAO agriculture organization

FCC fluid catalytic cracking

ICP integrated catalytic pyrolysis

MTO methanol to olefin

Global energy consumption is rising due to the increasing dependence of our lifestyle

to energy and increasing world’s population Transportation section is one of the mainenergy consumers with 20% share of total energy consumption Discovery of crude oilopened new window for manufacturing energy carriers and chemicals However,declining fossil hydrocarbon sources and increasing demand for fuels and some down-stream products are driving governments and industries toward exploring new sourcesfor manufacturing fuels and associated chemicals In addition to this, emission ofgreenhouse gases (GHG) is still a major challenge of crude oil associated industries

Bioenergy Systems for the Future http://dx.doi.org/10.1016/B978-0-08-101031-0.00004-1

© 2017 Elsevier Ltd All rights reserved.

Hence, proposing new routes for the production of energy carriers and chemicals thatare more environmental friendly is currently state of the art (Balat, 2011; Huber et al.,2006; Mortensen et al., 2011; Nigam and Singh, 2011; Sorrell et al., 2010; van Ruijvenand van Vuuren, 2009).

Gasoline and olefins are of the main products obtained directly or indirectly from sil fuels There are different routes for the production of gasoline and olefins.Gasoline, which is the primary liquid fuel for the internal combustion engines, isconventionally produced from crude oil The composition of gasoline is various anddepends on the initial crude oil source and the applied refinery process Gasoline ismainly a mixture of organic compounds such as straight chain, branched, and cyclicaliphatics, aromatics, and additives and blending agents A typical gasoline contains4%–8% alkanes, 25%–40% isoalkanes, 2%–5% alkenes, 3%–7% cycloalkanes,l%–4% cycloalkenes, and 20%–50% aromatics (volume percent) Refineries thatare responsible for gasoline manufacturing blend various refinery streams with differ-ent characteristics to produce gasoline Straight-run gasoline (naphtha) directly dis-tilled from crude oil, reformate obtained by catalytic reformer with high aromaticand low alkene contents, catalytic cracked gasoline (catalytic cracked naphtha)obtained by catalytic cracking of naphtha with moderate aromatics and high alkenecontents, and hydrocrackate obtained from hydrocracker, with moderate aromaticcontents, are some refinery streams blended in different manner to produce differentgrades (with different octane number) of gasoline (Meyers, 2004; Parkash, 2003;Speight, 2015) It is possible to produce gasoline from methanol In this process, meth-anol is primarily converted to dimethyl ether (DME) followed by further conversion ofDME to light and higher paraffins, aromatics, and naphthenes by applying zeolite cat-alysts (Keil, 1999; Olsbye et al., 2012; St€ocker, 1999)

fos-Olefins (also named alkenes) are aliphatic hydrocarbon compounds with pairs of bon atoms connected by double bonds Compared with equivalent saturated paraffins(i.e., paraffins with the same carbon number (CN)), unsaturated molecules of olefinscontain two less hydrogen atoms Hence, olefins tendency to reaction is more thanparaffins Their more reactivity than paraffins is due to the presence of pi-typecarbon-carbon bonds or allylic CH centers (McMurry, 1996; Wade, 2006) Similar toparaffins, olefins are colorless, nonpolar, inflammable, and almost odorless compounds.Solubility of olefins in water is low At conventional pressures and temperatures, olefinswith CN up to four are in gas state, and those with more CN are in liquid state Because

car-of participating in a wide range car-of reactions (e.g., hydration to alcohols, polymerization,and alkylation), olefins play a crucial role in petrochemical industry Olefins arefeedstocks for the production of a large variety of industrial chemicals such as polymers,adhesives, detergents, and solvents Ethylene and propylene are building blocks inmanufacturing plastic products Higher olefins such as polyolefins and alpha-olefinsare used as lubricants and comonomers, respectively (Bender, 2014; Rahimi andKarimzadeh, 2011; Sadrameli, 2016; Xieqing et al., 2006; Zakaria et al., 2013) Twomajor types of synthetic polymers produced from olefins are polyethylene and

polypropylene Polyethylene, which has a linear structure, is primarily utilized in theproduction of utility fabric, rope, and twine Polypropylene with a tridimensional struc-ture has a wide variety of applications such as textiles, packaging, plastic parts, and recy-clable containers (Kadolph, 2012; Zakaria et al., 2013).

Generally, there exist monoolefins, diolefins, and triolefins in which there are,respectively, one, two, and three double bonds in their structures Acyclic monoolefinswith general formula of CnH2 (in whichn is an integer) are rarely found in the nature Infact, they are produced in large scales in petrochemical plants Pioneer technologieshave been applying cracking of petroleum oils for large production of olefins, especiallymonoolefins (Zakaria et al., 2013) Thermal cracking, fluid catalytic cracking (FCC),and hydrocracking are commercial processes by which larger hydrocarbon moleculesare broken down to smaller ones such as olefins (Bender, 2014; Rahimi andKarimzadeh, 2011; Sadrameli, 2016; Xieqing et al., 2006) However, olefin productionfrom waste material sources is currently state of the art (Pyl et al., 2011) In fact, declin-ing sources of fossil fuel and environmental regulations are motivations for exploringnew routes to produce olefins (Fogassy et al., 2010; Hew et al., 2010; Kwon et al., 2011;Perego and Bosetti, 2011; Rezaei et al., 2014; Serrano-Ruiz and Dumesic, 2011)

Noticeable worldwide increase in the production of olefins is observed in the recentyears.Fig 4.1shows the trend of ethylene capacity growth from different areas up to

2011 (Zakaria et al., 2013) In spite of this, based on a global study over the outlook ofethylene and propylene market, there is a concern for the increasing production cost oflight olefins Such an increase may be due to the raising cost of raw material (Zakaria

et al., 2013) Hence, technologies utilizing material with lower cost could potentiallylead to lower cost of olefin production Besides, the production of olefins from hydro-carbon sources such as naphtha may lead to GHG emissions (Rahimi and Karimzadeh,2011; Rezaei et al., 2014) Many environmental issues such as change in climatepattern, global warming, and biodiversity defects are caused by increasing GHG emis-sions Hence, applying new routes that employs cheaper raw material and producesless GHG emissions is of a great interest (Nigam and Singh, 2011)

There is a similar statement for gasoline Although fossil fuels are the main source

of liquid fuels such as gasoline and downstream petrochemical products, their renewable and nonsustainable nature and subsequent environmental defects are moti-vations to search for new alternatives with low carbon dioxide emissions andcompatible and comparable energy efficiency (Huber and Corma, 2007; Huber

non-et al., 2006; Mortensen non-et al., 2011)

Biomass is an abundant source of carbon In this regard, green olefin or bio-olefin(i.e., olefin produced from biomass) and biogasoline could be considered as rivals forconventional olefins and gasoline produced from hydrocarbon sources Renewabilityand sustainability are the advantages of bio-olefins and biogasoline production overconventional routes, which may cause them to have a premium market in the nearfuture (Huber and Corma, 2007; Huber et al., 2006; Nigam and Singh, 2011;Zakaria et al., 2013)

Light olefins/bio-gasoline production from biomass 89

4.4 Feedstocks obtained from biomass

Exploring cheap and available biomass feedstock is the first step in further bioproductmanufacturing In this regard, biomass feedstocks could be obtained from the follow-ing sources (Huber and Corma, 2007):

l Waste materials such as urban residues, residues of crop, wood, and agricultural wastes

l Woodland products such as trees, shrubs, wood, and residues of logging

l Energy crops and starch crops such as corn, wheat, barley, sugar crops, grasses, andvegetable oils

l Aquatic sources such as water weed, water hyacinth, and algae

According to the sources of biomass feedstocks, cellulosic biomass, starch/sugar mass, and triglyceride biomass are three major categories (Huber and Corma, 2007)

bio-In a general point of view and regardless of local regulations, cellulosic biomass hasthe less cost However, the technology of cellulosic biomass conversion imposes extracharges On the other hand, cellulosic biomass is the cheapest, the most available, andthe most challenging one to convert into bioproducts due to its solid stated and lowenergy density (Huber and Corma, 2007; Huber et al., 2006) Due to the effect of bio-mass feedstock on the composition of subsequent bioproducts and yield of olefins or

Fig 4.1 Trends of ethylene capacity growth from different areas up to 2011

Data from Zakaria, Z.Y., Amin, N.A.S., Linnekoski, J., 2013 A perspective on catalyticconversion of glycerol to olefins Biomass Bioenergy, 55, 370–385

gasoline production, characteristics of different biomass feedstocks are of a greatimportance Hence, they are discussed in this section.

Cellulosic biomass includes cellulose, hemicellulose, and lignin as three majorgroups in which cellulose and hemicellulose are abundant more than lignin In fact,

up to 90% of biomass obtained from earth (i.e., terrestrial biomass) is made of lose and hemicellulose More details of their structure could be found elsewhere(Huber and Corma, 2007; Lynd et al., 1991; Wyman et al., 2005b) Processing cellu-losic biomass is still a challenge due to difficulties in converting solid-state biomass

cellu-to fluid (Kamm et al., 2006; Lynd et al., 1999; Mosier et al., 2005; Wyman et al.,2005a,b) Cellulosic biomass is processed and converted to fluid products using thefollowing processes (Huber and Corma, 2007; Huber et al., 2006):

l Hydrolysis in which aqueous sugar solutions are produced

l Pyrolysis and liquefaction in which bio-oils are produced

l Gasification in which liquid fuels are produced

More details of the aforementioned processes for cellulosic biomass processing will

be discussed in the following sections

Starch/sugar biomass (also called edible biomass) is almost obtained from bles Due to the amorphous structure, starch/sugar biomass could be converted tosugars or fuels in a procedure easier than cellulosic biomass Hence, it is utilized

vegeta-as a valuable feedstock for bioalcohol production Bioethanol is produced by the mentation of fermentable sugars initially obtained from biomass (Huber et al., 2006).Triglycerides (also known as fats) are obtained from vegetable oils, animal fats, andaquatic biomass such as algae and could be converted into glycerol and fatty acids.Besides, they could be upgraded to a suitable fuel by transesterification into biodiesel(i.e., alkyl fatty esters) and glycerol (Huber et al., 2006) Conversion of the obtainedglycerol into olefins is currently state of the art (Corma et al., 2008; Murata et al.,2008; Zakaria et al., 2013) The main challenge with the triglycerides biomass feed-stocks (such as vegetable oils) is their higher processing cost comparing that ofcellulosic biomass (Huber et al., 2006; Zakaria et al., 2013) The type of biomass feed-stocks used to obtain bio-oil and their physical and chemical properties (such aselemental composition, chemical composition, water content, density, viscosity, acidvalue, calorific value, and high heating value) were comprehensively summarized by

fer-Stedile et al (2015)

There are various routes to produce olefins and gasoline from biomass A graphic resentation of the possible routes to produce olefins and gasoline from biomass isshown inFig 4.2 The most probable route to produce olefins and gasoline from bio-mass is conversion of cellulosic biomass into bio-oil followed by a second processsuch as catalytic upgrading (Huber and Dumesic, 2006; Huber et al., 2006).Bio-oil, which is a mixture of more than 400 various compounds, is predominantlyobtained from cellulosic biomass by either pyrolysis (Bridgwater, 2012; Huber andLight olefins/bio-gasoline production from biomass 91

rep-Corma, 2007; Huber et al., 2006; Isahak et al., 2012; Mohan et al., 2006; Papari andHawboldt, 2015; Sharma et al., 2015) or liquefaction (Behrendt et al., 2008; Elliott

et al., 1991; Toor et al., 2011) Hence, a vast variety of biomass feedstocks such aswood and agricultural and forest wastes could be utilized for the production of bio-oil However, bio-oil production from algae is currently state of the art (Saber

et al., 2016) Depending on the biomass feedstock, method of bio-oil production,and operating conditions, various compounds such as aromatics, phenols, aldehydes,alcohols, esters, ketones, and acids could exist in the obtained bio-oil (Elliott et al.,1991; Huber et al., 2006) Pyrolysis is a process in which the biomass feedstock iswarmed up to high temperature (i.e., 375°C–525°C) in a finite time and in the absence

of air Consequently, a gaseous product is obtained, which is then condensed to liquid(Bridgwater, 2012; Huber and Corma, 2007; Huber et al., 2006; Isahak et al., 2012;Mohan et al., 2006; Papari and Hawboldt, 2015; Sharma et al., 2015) Liquefaction is aprocess at high pressures (up to 200 atm) and lower temperatures (i.e., 250°C–325°C).High pressure is a means of controlling reaction rate and mechanism in order to gen-erate liquid bio-oil (Behrendt et al., 2008; Elliott et al., 1991; Huber et al., 2006; Toor

et al., 2011) Production of bio-oil by pyrolysis process requires lower cost However,the bio-oil obtained by pyrolysis has higher oxygen content comparing that of lique-faction process (Huber et al., 2006)

Hy drolysis

Gasifica tion

Ethanol

Aromatics

Liquid alkanes hydrogen

Etherified gasoline

Liquid fuels olefins gasoline

Lignin upgrading

Syngas (CO + H2)

Bio-oil

Aqueous sugars

Lignin

Fig 4.2 Possible routes to produce olefins and gasoline from cellulosic biomass

Data from Huber, G.W., Iborra, S., Corma, A., 2006 Synthesis of transportation fuels frombiomass: chemistry, catalysts, and engineering Chem Rev 106(9), 4044–4098

As mentioned above, heating biomass feedstock and its thermal decomposition in theabsence of oxygen for bio-oil production is called pyrolysis Production of solid, liquid,and even gas during pyrolysis depends mainly on the residence time, rate of heating, andtemperature range Effects of these parameters on the state of final product in differentpyrolysis processes are given inTable 4.1(Huber et al., 2006; Klass, 1998) As can beseen, in slow pyrolysis (i.e., conventional pyrolysis) that applies long residence time andlow-to-medium heating rate, large amount of solid (charcoal) is produced Although itcould be utilized as a solid fuel in the further processes, the production of charcoalreduces bio-oil yield Hence, fast pyrolysis (i.e., flash pyrolysis or pyrolysis with shortresidence time and high heating rate) is more favorable Fast pyrolysis processes withhigh yields up to 80% have been reported in the literature (Bridgwater and Peacocke,2000; Mohan et al., 2006) On the other hand, low temperature and long residence timemake the reacting mixture proceed toward the production of charcoal, and high temper-ature and short residence time favor the production of gas Optimum conditions for theproduction of liquid are moderate temperature and short residence time (Bridgwater,2012; Huber et al., 2006).

With the aim of higher bio-oil production and yield, various researchers havefocused on designing and developing different reactor configurations on a variety

of biomass feedstocks.Bridgwater (2012)collected properties of well-studied reactorconfigurations of fast pyrolysis such as fixed-bed, bubbling fluid beds, circulatingfluid beds and transported beds, rotating cone, and ablative pyrolysis reactor In thisstudy, performance of these reactors was compared according to their production

Table 4.1 State of products in different pyrolysis processes

Process

Residencetime Temperature (°C)

Heatingrate

State ofproductConventional

pyrolysis

Flash pyrolysis <1 s 1000–3000 Very high Gas

pp 1 –27, (Chapter 1).

Light olefins/bio-gasoline production from biomass 93

capacity, heating capability, char production, and separation Other configurationssuch as entrained flow reactor, vacuum pyrolysis reactor, screw and augur kilns,and microwave pyrolysis were also investigated (Bridgwater, 2012) Details of com-mercial pyrolysis processes for bio-oil production could be found elsewhere(Bridgwater and Peacocke, 2000; Bridgwater, 2012; Czernik and Bridgwater, 2004;Elliott et al., 1991; Mohan et al., 2006).

As mentioned previously, liquefaction process occurs at high pressure and lowertemperatures As a result, a bio-oil, which is insoluble in water, is produced.Catalyst type, pressure, and gases are the means for controlling the rate and mech-anisms of the desired reactions in order to gain to high-quality liquid oil In thisprocess, the reactor is fed with a slurry stream composed of biomass feedstock

in a liquid solvent, reducing gas, and catalyst Reducing gases are often hydrogen

or carbon monoxide, and catalysts could be alkali, metals, nickel, or ruthenium.Depending on the utilized liquid solvent, hydrothermal liquefaction, solvolysis,and hydropyrolysis are possible (Behrendt et al., 2008; Elliott et al., 1991;Moffatt and Overend, 1985; Toor et al., 2011; Vanasse et al., 1988) In addition

to water, ethylene glycol, creosote oil, and methanol, produced bio-oil could berecycled and used as the solvent (Moffatt and Overend, 1985) In hydropyrolysis,liquefaction of biomass feedstock occurs in the presence of high-pressure hydrogenand an appropriate heterogeneous catalyst (Moffatt and Overend, 1985) Solvolysis

is a high-pressure process in which ethylene glycol, methanol, phenol, and creosoteoil are used as solvent Hydrothermal liquefaction, which serves water as solvent,

is the most attractive route due to lower cost Nevertheless, recycling a fraction ofoutput bio-oil into the reactor entrance results in higher selectivity (Moffatt andOverend, 1985) A commercial liquefaction process for bio-oil production wasdeveloped by Goudriaan et al., (2008)

Typical properties of bio-oils obtained by fast pyrolysis and liquefaction andthose of conventional petroleum oil are compared in Table 4.2 (Czernik andBridgwater, 2004; Elliott and Schiefelbein, 1989; Huber et al., 2006; Miao

et al., 2004; Yuan et al., 2011) As can be seen, bio-oil obtained by fast pyrolysishas higher moisture and oxygen contents and lower carbon and hydrogen contents.Besides, it has lower heating value and viscosity Due to the presence of acidiccompounds, bio-oil obtained by fast pyrolysis has a pH in the range of acids.Higher heating value of liquefaction bio-oil is due to the presence of higher carboncontent and lower oxygen content However, higher viscosity of liquefaction bio-oil makes it unfavorable for further processing and applications such as enginefuel In fact, high oxygen content of the bio-oil has significant effects on the homo-geneity, polarity, heating value, viscosity, blending, and acidity of the bio-oil.Solid production and distillation residue are some drawbacks of fast pyrolysisbio-oil Properties of more bio-oil samples in the literature were summarized

by Gollakota et al (2016) Liquefaction bio-oils have properties more similar toconventional petroleum oil Hence, it seems to be more beneficial in the long term.However, in an economic point of view, required capital cost for high-pressurefacilities in the liquefaction process is the main reason of industries to focus

on the production of bio-oil by fast pyrolysis Besides, upgrading liquefaction

Table 4.2 Typical properties of bio-oils and conventional petroleum oil

Property

Pyrolysis bio-oil(Huber et al., 2006)

Pyrolysis bio-oil(Miao et al., 2004)

Liquefaction bio-oil(Huber et al., 2006)

Liquefaction bio-oil(Yuan et al., 2011)

Petroleum oil(Huber et al.,

bio-oil is declared to have no benefit over fast pyrolysis bio-oil (Elliott et al., 1990,1991; Elliott and Schiefelbein, 1989; Goudriaan et al., 2008; Huber et al., 2006;Towler et al., 2004) It should be mentioned that the bio-oil is a low-value fueldue to the presence of high oxygen content Hence, bio-oil upgrading and theproduction of value-added products such as gasoline and olefins are currently state

of the art

A possible route to produce bio-olefin and biogasoline from biomass feedstock isgasification The obtained syngas from biomass feedstock could be used for theproduction of methanol followed by methanol-to-olefin (MTO) and methanol-to-gasoline (MTG) processes In gasification process, biomass reacts with air, oxygen,and/or water vapor to produce carbon monoxide, carbon dioxide, hydrogen, meth-ane, and nitrogen (Babu, 2005; Klass, 1998; Milne et al., 1998; Mudge et al., 1985;Pereira et al., 2012; Puig-Arnavat et al., 2010; Sutton et al., 2001) Different reac-tions such as pyrolysis, partial oxidation, steam gasification, water-gas shift(WGS), and methanation occur in the gasification process (Evans and Milne,1987; Huber et al., 2006; Klass, 1998) Composition of the gas produced by gas-ification depends mainly on the biomass feedstock, gasification procedure, and thegasifying agent (Huber et al., 2006; Narvaez et al., 1996) Possible remedies todecrease the generation of the tar (higher-molecular-weight hydrocarbons) in thegasification of biomass feedstock were well investigated by different researchers(Baker et al., 1987; Encinar et al., 1998; Mudge et al., 1985; Rapagnà et al.,2000; Sutton et al., 2001; Tomishige et al., 2004) Regarding how to contact bio-mass feedstock and gas stream, three main reactor types for gasification are updraftgasifier, downdraft gasifier, and fluidized-bed gasifier Fluidized-bed gasifier issuitable for large-scale productions More details on different gasifiers and theircharacteristics could be found elsewhere (Huber et al., 2006) The produced syngas

by gasification is converted to valuable chemicals in different routes Hydrogenproduction by WGS reaction (Farrauto et al., 2016; Fu et al., 2003, 2005;Haruta et al., 1993; Huber and Dumesic, 2006; Joensen and Rostrup-Nielsen,2002; Kim et al., 2004; Levin et al., 2004; Rostrup-Nielsen, 2001; Zhang et al.,

2004), methanol synthesis (Chinchen et al., 1988; Farrauto et al., 2016; Klier,1982; Rezaie et al., 2005; Saeidi et al., 2014a; Wender, 1996), Fischer-Tropschsynthesis to produce alkanes (Dry, 2002; Iglesia et al., 1993; Martı´nez andLo´pez, 2005; Saeidi et al., 2014b, 2015), and production of ethanol by fermentation(Datar et al., 2004; Klasson et al., 1993; Younesi et al., 2005) are subsequentprocesses of syngas production units The produced methanol is converted toolefins (i.e., MTO process) or gasoline (i.e., MTG process) by zeolites orsilicoaluminophosphate (SAPO) catalysts (Izadbakhsh and Khatami, 2014;St€ocker, 1999; Wender, 1996) In fact, gasification of biomass feedstocks followed

by methanol synthesis and MTO/MTG process is a three-step distinct route to duce bio-olefins and biogasoline

4.7 Bio-oil upgrading

In the previous sections, the properties of bio-oil were discussed (i.e.,Table 4.2) Aspreviously mentioned, more than 400 various chemical compounds have been iden-tified in bio-oil Composition of obtained bio-oil depends mainly on the biomassfeedstock and the conditions of the process More detailed chemical compositions

of a bio-oil samples are summarized inTables 4.3and4.4(Rezaei et al., 2014) Ascan be seen, there exist unsaturated compounds leading to undesired reactions andlow stability of the bio-oil Hence, the properties of the bio-oil change with time(Fisk et al., 2009; Grac¸a et al., 2009, 2010; Li et al., 2011; Rezaei et al., 2014) Besides,the presence of oxygenated compounds leads to high corrosion and low heating value

of the bio-oils To avoid such drawbacks and enhance the properties of bio-oil with theaim of producing olefins and gasoline, a supplementary process called bio-oilupgrading is necessary Most of the methods for bio-oil upgrading are chemical.However, there are some reported physical methods such as filtration (Diebold

et al., 1994; Pattiya and Suttibak, 2017; Shihadeh, 1999), solvent addition (Dieboldand Czernik, 1997), and forming emulsions (Baglioni et al., 2008; Chiaramonti

et al., 2003a,b; Ikura et al., 2003) in the literature Chemical upgrading is a complexreaction network due to the presence of diverse compounds in the bio-oil Hydroge-nation, hydrodeoxygenation, cracking, hydrocracking, decarboxylation, polymeriza-tion, and decarbonylation are possible reactions in the bio-oil upgrading (Adjaye andBakhshi, 1995a,b; Wildschut et al., 2009)

In a general point of view, two different chemical routes for bio-oil upgrading arehydrodeoxygenation (or hydrotreating) and catalytic upgrading (or catalytic crack-ing) Nevertheless, steam reforming of the bio-oil or char for syngas or hydrogenproduction is an alternative route for converting bio-oil into a range of fuels(Czernik et al., 2002; Garcia et al., 2000; Sa´nchez et al., 2005; Wang et al., 1997)

Hydrodeoxygenation (HDO) (also called hydrotreating) is a high-pressure andmoderate-temperature process in which oxygen is rejected by a catalytic reaction withhydrogen In this regard, present oxygenated compounds in the bio-oil react with high-pressure hydrogen in the presence of a heterogeneous catalyst to form water andsaturated carbon-carbon bonds (Elliott et al., 1991, 2009; Elliott, 2007; Gollakota

et al., 2016; Saidi et al., 2014) HDO of bio-oil is performed at 250°C–600°C(Huber and Corma, 2007; Venderbosch et al., 2010) and pressures up to 300 bar(Bridgwater, 2012; de Miguel Mercader et al., 2010; Elliott et al., 2009; Furimsky,2000; Huber et al., 2006; Venderbosch and Prins, 2010) High pressure leads to highersolubility of hydrogen in the bio-oil and its higher proximity to the catalyst surface.Consequently, higher reaction rate and lower coke formation are managed (Kwon

et al., 2011; Venderbosch et al., 2010) During HDO, hydrogenation of present matics in the bio-oils must be avoided Otherwise, it would lead to higher hydrogenconsumption and even lower octane number of the product Therefore, selecting the

aro-Light olefins/bio-gasoline production from biomass 97

Table 4.3 Composition of bio-oils obtained by fast pyrolysis of different biomass feedstocks

Softwood(Oasmaa andMeier, 2005)

Corncob(Mullen et al.,

2010)

Corn stover(Mullen et al.,

2010)Reactor type Transport-bed Transport-bed Rotating-bed Fluidized-bed Fluidized-bed

Table 4.4 Detailed chemical composition of bio-oil derived

by fast pyrolysis of pine sawdust

Data from Gayubo, A., Valle, B., Aguayo, A., Olazar, M., Bilbao, J., 2010 Pyrolytic lignin removal for the valorization

of biomass pyrolysis crude bio-oil by catalytic transformation J Chem Technol Biotechnol 85(1), 132 –144; Rezaei, P.S., Shafaghat, H., Daud, W.M.A.W., 2014 Production of green aromatics and olefins by catalytic cracking of oxygenate compounds derived from biomass pyrolysis: a review Appl Catal A General 469, 490 –511.

heterogeneous catalyst and the process conditions is crucial Industrial hydrotreatingcatalysts such as sulfided cobalt/molybdenum and nickel/molybdenum and platinum-supported alumina or aluminosilicate (Bui et al., 2009; Fisk et al., 2009; Furimsky,2000; Sheu et al., 1988; Su-Ping, 2003; Xu et al., 2009; Zhang et al., 2005), vanadiumnitride (Ramanathan and Oyama, 1995), ruthenium (Elliott and Hart, 2009; Mahfud

et al., 2007), and SBA-15 (Tang et al., 2009) have been investigated as the neous catalysts in the previous studies A number of research institutions working onthe HDO of bio-oil were reported in a recent review byBridgwater (2012) Typicalproperties of an upgraded bio-oil by HDO are reported and compared with twobio-oils inTable 4.5 Clearly, there is an increase in carbon content and a decrease

heteroge-in oxygen content and density As a result, higher heatheteroge-ing value and lower viscosityare obtained

Saidi et al (2014) reviewed HDO of lignin-derived bio-oils such as anisole,guaiacol, and phenol with focus on HDO chemistry, reaction pathways, catalystsactivities, selectivities of components, and stabilities Without presenting an econom-ical assessment, they provided recommendations for further research and developingHDO as a sustainable option for fuel processing (Saidi et al., 2014) Recently, a sum-mary of studies associated with bio-oil upgrading by applying HDO was collected andcompared by Gollakota et al (2016) From this review, it was concluded that themechanism of involved reaction or the inside chemistry of HDO is not well under-stood Besides, catalyst formulation is another concern with this field Despite lots

of efforts for presenting efficient catalysts, they are limited to laboratory-scale cations instead of industrial ones In spite of extensive researches on the bio-oilupgrading by HDO, hydrogen supply and relatively high cost for the high-pressure

appli-Table 4.5 Properties of two bio-oils and an upgraded bio-oil by HDO

Property

Liquefactionbio-oil

Pyrolysisbio-oil

Upgraded bio-oil

by HDOElemental composition (wt%)

facilities are still challenges (Cottam and Bridgwater, 1994; Elliott andNeuenschwander, 1997; Gollakota et al., 2016) However, integrated processes couldrun the art of in situ biohydrogen production from biomass feedstocks (Fisk et al.,

2009) Accordingly, catalyst development, understanding the mechanism of carbonformation, kinetics of HDO, hydrogen source, and possibility of low-pressure processare main fields still need to be studied before the implementation of industrial bio-oilHDO process (Gollakota et al., 2016)

In spite of the advantages of HDO for bio-oil upgrading to liquid fuels with highheating value, it is not considered as a route for the production of bio-olefins and evengasoline-type fuels Main components obtained from catalytic HDO of lignin-derivedanisole over various catalyst and their selectivities are given in Table 4.6 Clearly,phenol, o-cresol, and 2,6-dimethylphenol are the main components of the hydro-deoxygenated anisole bio-oil However, in some cases, a considerable amount ofbenzene is produced (Saidi et al., 2014) Hence, a different route for bio-oil upgradingwith the aim of bio-olefin and biogasoline production is of a great interest

Although HDO is not a process for direct production of olefins from bio-basedsources, it could provide valuable feed for conventional processes of olefin produc-tion In this regard,Pyl et al (2011)proposed an alternative procedure for the produc-tion of light olefins from low value and waste materials such as fats, greases and otherrenewable fractions based on HDO and conventional steam-cracking processes Thefirst step in this process was producing high-quality paraffin-rich diesel and renewable

Table 4.6 Product distribution in anisole upgrading by HDO

over various catalysts

Data from Huuska, M., 1986 Effect of catalyst composition on the hydrogenolysis of anisole Polyhedron 5(1),

233 –236; Saidi, M., Samimi, F., Karimipourfard, D., Nimmanwudipong, T., Gates, B.C., Rahimpour, M.R., 2014 Upgrading of lignin-derived bio-oils by catalytic hydrodeoxygenation Energy Environ Sci 7(1), 103 –129.

Light olefins/bio-gasoline production from biomass 101

naphtha from catalytic HDO of triglycerides and/or fatty acids obtained from bio-oils

to The free oxygenate renewable naphtha stream would be potential feed for the duction of ethylene by steam cracking Ethylene yield of 31 wt%, propylene yield of17.5 wt%, and gasoline yield of 15 wt% were obtained The obtained results of thisstudy reveal that this process can be comparable with the typically conventional pro-duction of olefins from fossil sources (Pyl et al., 2011) The Bio-Synfining processproducing bio-based hydrocarbon feeds for conventional steam crackers is shown

pro-inFig 4.3(Abhari et al., 2010, 2013; Pyl et al., 2011)

Bio-oil could be upgraded using cracking at atmospheric pressure and temperaturerange of 300°C–650°C in the presence of solid catalyst such as zeolites, silica-alumina, and other molecular sieves (Gollakota et al., 2016) Zeolites are the mostutilized solid catalyst for bio-oil upgrading (Mortensen et al., 2011; Rezaei et al.,

2014) Zeolites, that is, crystalline microporous inorganic oxides, are broadly utilized

in the various industries with the aim of separation, purification, and refining of fluidstreams These solid acid catalysts are widely used in chemical, petrochemical, and oil

Water

C15-C18+

C10-C15 C5-C9 C3-C4

C3-C18+

Hydrogen makeup

Hydrocracker

Hydro-deoxygenator

Recycle compressor

LPG

Naphta

Jet Feed

Fractionation

Fig 4.3 Schematic of the Bio-Synfining process for the production of bio-based hydrocarbons.Modified from Abhari, R., Tomlinson, L., Havlik, P., Jannasch, N., 2010 Process forco-producing jet fuel and LPG from renewable sources Google patents; Abhari, R.,

Tomlinson, H.L., Roth, G., 2013 Biorenewable naphtha Google patents; Pyl, S.P.,

Schietekat, C.M., Reyniers, M.-F., Abhari, R., Marin, G.B., Van Geem, K.M., 2011 Biomass toolefins: cracking of renewable naphtha Chem Eng J 176–177, 178–187

refining industries for the production of fuels and energy carriers Extensive tion of zeolites is due to their unique structural and compositional characteristics such

applica-as high surface area, high pore volume, controllable adsorption properties, adjustabledimensions of channels and cages, tunable hydrophobicity, and shape selectivity(Bakhtyari and Mofarahi, 2014; Corma, 1997; Mofarahi and Bakhtyari, 2015;Primo and Garcia, 2014; Reyniers and Marin, 2014; Sani et al., 2014) Zeolites andsolid catalysts are utilized to reject oxygen, enhance thermal stability, and thusupgrade the bio-oil Generally, fluid streams containing hydrocarbons (both aliphaticsand aromatics), water-soluble organic compound, oil-soluble organic compounds,water, light gaseous compounds (such as lighter alkanes, carbon dioxide, and carbonmonoxide), and coke are generated by zeolite upgrading (also called zeolite cracking)

In the zeolite upgrading process, a variety of chemical reactions such as deoxygenation,cracking, aromatization, dehydration, decarbonylation, isomerization, dehydrogena-tion polymerization, and coke formation occur A graphic representation of the overallreaction pathway and probable chemical reactions during zeolite cracking of bio-oil

is shown inFig 4.4 It is possible to regulate the chemical route to obtain the desiredproduct by controlling operating conditions and catalyst characteristics Applyingzeolites for bio-oil upgrading is advantageous due to the atmospheric condition ofthe process and temperature conditions similar to those of bio-oil production Besides,

it does not require hydrogen Hence, operating costs for high-pressure facilities andhydrogen supply and storage are omitted, which leads to economic benefits overHDO In spite of these, low hydrocarbon yields and the formation of polycyclic aro-matics and coke are still major challenges of zeolite upgrading process (Huber andCorma, 2007; Huber et al., 2006; Mortensen et al., 2011; Rezaei et al., 2014) In prin-ciple, catalytic cracking of bio-oil is similar to that of crude oil refinery for convertingheavier hydrocarbons to valuable light products Hence, main facilities that are active

in crude oil refinery could be applied for biorefinery and coprocessing of bio-oil withcrude oil fractions with some reconfiguration (Huber and Corma, 2007) In addition tothis, integrating pyrolysis and zeolite cracking for simultaneous bio-oil productionand upgrading are currently state of the art (Galadima and Muraza, 2015) Such acapability is introducing zeolite cracking as a potential single-step route for upgradinginstead of two-step route of bio-oil production and HDO upgrading Recently,

Gollakota et al (2016)conducted a summary of literature key works on upgradingbio-oil by catalytic cracking A comprehensive detail on the catalytic cracking andother proposed upgrading techniques are reviewed Advantages and disadvantages

of catalytic cracking over other upgrading techniques were compared scrupulously.Olefins (especially light olefins) and aromatics (or gasoline) are major compoundsobtained by zeolite upgrading of bio-oil Accordingly, efficient processes for theproduction of olefins and gasoline from biomass-derived bio-oil are rivals for conven-tional technologies producing these compounds from crude oil (Huber and Corma,2007; Rezaei et al., 2014) The main objective of this chapter is introducing possibleroutes for the production of olefins and gasoline from biomass/bio-oil feedstocks(i.e., bio-olefins and biogasoline) In this regard, the most widely studied and the mostefficient route (i.e., zeolite cracking of biomass/bio-oil) will be investigated withdetails in the following sections

Light olefins/bio-gasoline production from biomass 103

to study the production of light olefins from biomass feedstocks or bio-oil.

In a recent review, Rezaei et al investigated biomass/bio-oil to olefins (BTO) ies up until 2014 (Rezaei et al., 2014) Details of these studies and the ones that aremore recent are tabulated in Table 4.7 These studies are classified according to

stud-Aromatization alkylation isomerization

Deo

xygena tion

cracking

oligomariza tion

Polymerization

2014 Production of green aromatics and olefins by catalytic cracking of oxygenate compoundsderived from biomass pyrolysis: a review Appl Catal A General 469, 490–511

Table 4.7 Catalytic upgrading of biomass/bio-oil feedstock with the aim if olefins production

Catalyst (Si/

Al ratio) Feed Conv (%) Reactor T (°C)

Feed/catratio

Olefinyield Ethylene Propylene Butylene Coke Ref.HZSM-5

(30)

feed/gcat h

19.1 wt%

of feed

38.7 wt

% ofolefins

5a (30)

et al.(2012)La/HZSM-5

21.2 C% ofgasproducts

La content,

6.0 wt%

et al.(2012)La/HZSM-5

Continued

Table 4.7 Continued

Catalyst (Si/

Al ratio) Feed Conv (%) Reactor T (°C) Feed/catratio

Olefinyield Ethylene Propylene Butylene Coke Ref.La/HZSM-5

Fluidized-bed

600 0.35 g

feed/gcat h

9.4 C% offeed

et al.(2012)

Fluidized-bed

et al.(2012)ZSM-5 Pine wood

et al.(2010)HZSM-5

Continued

Table 4.7 Continued

Catalyst (Si/

Al ratio) Feed Conv (%) Reactor T (°C) Feed/catratio

Olefinyield Ethylene Propylene Butylene Coke Ref.L-tartaric

HZSM-5

(30)

ofproducts

ChengandHuber(2012)HZSM-5

(30)

andHuber(2012)HZSM-5

(30)

andHuber(2012)HZSM-5

% ofproducts

6.3 wt%

ofproducts

2.2 wt%

ofproducts

et al.(2010)

H-Y zeolite n-Heptane 30.8 Fixed-bed 450 30 – 0.9 15.1 8.3 – Grac¸a

et al.(2010)Al-MCM-41

(20)

feed/gcat

ofproducts

1.1 wt%

ofproducts

0.7 wt%

ofproducts

et al.(2012)Al-MCM-41

(20)

et al.(2012)HZSM-5

(15)

et al.(2012)Pt/HZSM-5

(15)

et al.(2012)Pt/Meso-

(30)

ofproducts

7.9 C% ofproducts

1.4 C%

ofproducts

andHuber(2011)HZSM-5

Table 4.7 Continued

Catalyst (Si/

Al ratio) Feed Conv (%) Reactor T (°C) Feed/catratio

Olefinyield Ethylene Propylene Butylene Coke Ref.HZSM-5

et al.(2010b)

(25)

et al.(2011)Mg/

et al.(2011)None (sand) Prairie

cordgrass

et al.(2016)HZSM-5 Prairie

cordgrass

et al.(2016)2% Co/

(25.5)

(2015)

Continued

Table 4.7 Continued

Catalyst (Si/

Al ratio) Feed Conv (%) Reactor T (°C) Feed/catratio

Olefinyield Ethylene Propylene Butylene Coke Ref.5Ga/ZSM-5

Ga2O3,

6.13%

(2015)ZSM-5

system characteristics such as catalyst type, feedstock type, conversion, reactor type,temperature range, and feed to catalyst ratio and characteristics of the product such asolefin yield, coke yield, and components distribution Various biomass feedstocks andbio-oils have been studied by different authors However, most of the studies havefocused on the ZSM-5-type zeolites and fixed-bed reactors.

Catalytic bio-oil upgrading could be propelled toward higher production of olefins

by controlling operating conditions such as temperature and weight hourly spacevelocity (WHSV) In this regard,Gong et al (2011)investigated the effect of temper-ature and WHSV on BTO conversion in a fixed-bed reactor filled with HZSM-5 cat-alyst (Si/Al¼25) modified by lanthanum Maximizing olefin production by adjustingtemperature and WHSV was aimed in this study Based on the findings of this study,increasing temperature leads to cracking of oxygenated compounds and thus higherBTO conversion and enhanced yields of light olefins However, at temperatures above

600°C, second cracking of light olefins leads to lower yield of olefins Besides, higherethylene production and lower propylene and butylene production are outcomes ofincreasing temperature WHSV, which is a measure of feed mass flow rate to catalystweight ratio, strongly affects the BTO conversion and yields of olefins IncreasingWHSV leads to lower retention time and consequently lower BTO conversion andyields of olefins Besides, it gives rise to less ethylene and more butylene productiondue to preventing second cracking of lighter olefins (Gong et al., 2011) Similar obser-vations were reported byCheng and Huber (2011)for the conversion of furan to ole-fins over HZSM-5 (Si/Al¼25) in different temperature and WHSV ranges It is worthmentioning that feed and reactor types are determining factors in the BTO process

Gayubo et al (2009a)investigated the production of olefins from bio-oil + methanolmixture in a fluidized-bed reactor loaded with HZSM-5 (Si/Al¼80) Increasing spacetime results in increasing BTO conversion and yields of light olefins In addition tothis, higher BTO conversion and the production of olefins were managed by increas-ing temperature in the range of 400°C–500°C However, the effects of temperature onselectivities of ethylene, propylene, and butylene were different Constant ethyleneselectivities beside enhanced propylene and butylene selectivities were observed byincreasing temperature (Gayubo et al., 2009a)

Effect of alcohol type on the production of olefin by catalytic fast pyrolysis of wood over commercial ZSM-5 catalyst in a fluidized-bed reactor was studied by

pine-Zhang et al., (2012) Conversions of mixtures of biomass and various alcohols(i.e., methanol, 1-propanol, 1-butanol, and 2-butanol) were studied at different tem-peratures and WHSV Change of alcohol type strongly affects the yields of olefins andcomponents distribution Addition of alcohol to the feedstock leads to the production

of heavier olefins Besides, higher butylene production with increasing CN of alcohol

is gained (Zhang et al., 2012)

Change of feedstock results in different yields and product distribution This is due

to diversity of present compounds and their quantities, differences in their structures,and different hydrogen-to-carbon ratio (i.e., H/C) As previously mentioned, cellu-losic biomass feedstocks contain cellulose, hemicellulose, and lignin.Huang et al.(2012)studied the conversion of these biomass feedstock types to light olefins by cat-alytic pyrolysis in a fixed-bed reactor loaded with HZSM-5 (Si/Al¼25) catalyst

Light olefins/bio-gasoline production from biomass 113

particles In addition to this, the potential of rice husk, sawdust, and sugarcane bagassefor the production of olefins was examined The applied HZSM-5 catalyst was mod-ified by 6.0 wt% lanthanum Effect of temperature, residence time, and the feed tocatalyst ratio on the yields and selectivities of olefins was studied Biomass feedstockcontaining higher quantities of cellulose and hemicellulose led to higher product yield.Hence, the following order was observed for production yield:

cellulose> sugarcane bagasse > hemicellulose > rice husk > sawdust > lignin

In addition to this, higher yields of olefins were obtained from feedstocks with morecellulose or hemicellulose contents It is worth mentioning that except lignin, all thefeedstocks led to higher ethylene yield than those of propylene and butylene Inthe case of lignin, propylene yield was more than that of ethylene Therefore, it could

be concluded that with the change of biomass feedstock, mixtures of olefins with ferent compositions are obtained (Huang et al., 2012)

Production of olefins from glycerol (C3H8O3) was investigated in a recent review by

Zakaria et al (2013) Glycerol, which is an alcohol and oxygenated compoundobtained from biodiesel, is a promising, sustainable, and environmental friendly can-didate for the production of bio-olefins A list of studies for glycerol to olefins (GTO)conversion was collected and compared with conventional technologies for conver-sion of alcohols to olefins and hydrocarbons

The main challenge in GTO conversion is efficient oxygen elimination from erol and converting the hydrophilic molecule into a hydrophobic one Oxygen can beeliminated from glycerol molecule as water, carbon dioxide, or carbon monoxidethrough the following reaction (Corma et al., 2007; Zakaria et al., 2013):

glyc-C3H8O3! aCxH2x + 2Oy+bH2O +cCO2+dCO + eC (4.1)Selective production of olefins or even aromatics is the outcome of competition betweencracking, dehydration, hydrogen producing, and hydrogen transfer reactions Production

of olefins could be optimized by appropriate selection of the catalyst and operating ditions In this regard, through the catalytic cracking of glycerol, dehydration reactions onacid sites make the process proceed toward producing water and dehydrated compounds(Corma et al., 2007; Murata et al., 2008; Pathak et al., 2010; Zakaria et al., 2012) Steamreforming of dehydrated compounds leads to carbon monoxide and hydrogen Morehydrogen is produced through WGS reaction The dehydrated compounds react withthe hydrogen through hydrogen transfer reactions and thus produce olefins and aromatics.Another route to produce ethylene is decarbonylation reactions in which ethylene andcarbon monoxide are produced from acrolein Besides, aromatics and even heavier ole-fins may be produced by Diels-Alder and aldol condensation reactions of lighter olefinsand aldehydes (Corma et al., 2007; Zakaria et al., 2013).Corma et al (2007, 2008)

investigated catalytic conversion of GTO over various catalysts such as ZSM-5, Al2O3,and Y zeolites Yields of light olefins were observed to increase as a result of increasingtemperature and decreasing space velocity Besides, coke formation was decreased due toincreasing temperature The proposed general reaction network for catalytic conversion

of glycerol is schematically presented inFig 4.5(Corma et al., 2008; Zakaria et al., 2013)

In the studies conducted byHoang et al (2007a,b, 2010), the conversion of glycerol tohydrocarbons and fuels over HZSM-5 and Pd/ZnO catalysts was investigated The

J Catal 257(1), 163–171; Zakaria, Z.Y., Amin, N.A.S., Linnekoski, J., 2013 A perspective oncatalytic conversion of glycerol to olefins Biomass Bioenergy, 55, 370–385

Light olefins/bio-gasoline production from biomass 115

proposed reaction network is shown inFig 4.6 In a system operating under 400°C andatmospheric pressure, a gaseous stream mainly containing propylene and traces of eth-ylene was obtained in their study.

By comparing the most widely used methods for producing olefins,Zakaria et al.(2013)declared that GTO could be a sustainable method for olefins supply since glyc-erol is considered as a renewable source Furthermore, advances in the production ofbiodiesel will guarantee continuous glycerol supply (Campbell et al., 2011; Demirbasand Fatih Demirbas, 2011; Doan et al., 2011; Scott et al., 2010) However, efforts topropose the most effective GTO process are still ongoing

As concluded byGollakota et al (2016), to attain maximum product yield in alytic cracking of biomass-derived compounds (such as glycerol), the oxygen should

cat-be eliminated in the form of carbon dioxide and water instead of carbon monoxide andcoke This maximum yield depends on effective H/C ((H/C)eff.), which is defined bythe following equation (Gollakota et al., 2016):

oxy-Deoxygenation dehydration thermal decomposition

HZSM-5

Condensa tion

deh ydr ation

Fig 4.6 The proposed reaction network for the conversion of glycerol to hydrocarbonsand fuels

Modified from Hoang, T., Ballantyne, G., Danuthai, T., Lobban, L.L., Resasco, D.,

Mallinson, R.G., 2007a Glycerol to gasoline conversion In Spring National Meeting,AIChE; Hoang, T., Danuthai, T., Lobban, L., Resasco, D., Mallinson, R.G., 2007b Catalyticglycerol conversion In: The 2007 Annual Meeting; Hoang, T.Q., Zhu, X., Danuthai, T.,Lobban, L.L., Resasco, D.E., Mallinson, R.G., 2010 Conversion of glycerol to alkyl-aromaticsover zeolites Energy Fuels 24(7), 3804–3809; Zakaria, Z.Y., Amin, N.A.S., Linnekoski, J.,

2013 A perspective on catalytic conversion of glycerol to olefins Biomass Bioenergy 55,

370–385

yield based on carbon is 77% when converted to carbon dioxide, 66% when converted tocarbon monoxide, and 33% when converted to carbon (Gollakota et al., 2016):9

in fuel processing due to their high octane numbers and capability to be used as octaneenhancers in gasoline (Thring et al., 2000) Probable aromatic compounds in the cat-alytic upgrading of biomass/bio-oil feedstocks are presented inTable 4.8

Up until now, several researchers have attempted to enhance the yields ofaromatics in bio-oil upgrading processes In this regard, various microporous andmesoporous catalysts such as zeolites have been investigated for cracking ofbiomass/bio-oil with the aim of gasoline (or aromatics) production To obtain maxi-mum selectivities of aromatics besides minimum coke formation, acidity and shapeselectivity of catalyst must be adjusted Acidity of the catalyst is caused by Brønstedand Lewis acid sites (Engtrakul et al., 2016; Puertolas et al., 2015), and shape selec-tivity is adjusted by mass transfer effects and transition-state ones (Csicsery, 1983,1984; Smit and Maesen, 2008; Weisz, 1980)

In the review ofRezaei et al (2014), the yields of aromatics obtained by catalyticcracking of some bio-oil compounds up to 2014 are summarized Studies reported byRezaei et al and more recent ones are summarized inTable 4.9 Based on these results,HZSM-5-type zeolites are the most widely used catalysts for biomass/bio-oil to gas-oline (BTG) conversion These zeolites are shown to be the most effective ones for theconversion of present oxygenated compounds in the biomass/bio-oil feedstocks togasoline main compounds (i.e., benzene, toluene, alkylated benzenes, naphthalenes,and alkylated naphthalenes) (Evans and Milne, 1988; Mathews et al., 1985;Sharma and Bakhshi, 1991; Soltes and Milne, 1988) However, Y zeolites and acti-vated alumina were shown to be effective in the enhancement of aromatic production

in the catalytic pyrolysis of wood-derived biomass feedstock (Williams and Horne,

1995) HZSM-5 zeolites have higher yields of single-ring aromatics, whereas cation of Y zeolites leads to higher yield of naphthalene and alkylated ones (Rezaei

appli-et al., 2014) Capabilities of the other zeolite types such as H-Y, H-beta, H-mordenite,and H-ferrierite for BTG conversion were investigated by Mihalcik et al (2011).Acidity of catalyst, which is a function of Si/Al ratio, strongly affects the aromatic

Light olefins/bio-gasoline production from biomass 117