Investigating catalysts based on zsm 5 modified by phosphorus for propylene production from atmospheric residue

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY LE TRUNG NGHIA INVESTIGATING CATALYST BASED ON ZSM-5 MODIFIED BY PHOSPHORUS FOR PROPYLENE PRODUCTION FROM ATMOSPHERIC RESIDUE MASTER THESIS H

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY

LE TRUNG NGHIA

INVESTIGATING CATALYST BASED ON ZSM-5 MODIFIED BY PHOSPHORUS FOR PROPYLENE PRODUCTION FROM ATMOSPHERIC RESIDUE

MASTER THESIS

HO CHI MINH CITY, JULY 2019

Cán bộ hướng dẫn khoa học 1: TS Lê Phúc Nguyên

Cán bộ hướng dẫn khoa học 2: PGS TS Huỳnh Quyền

Cán bộ chấm nhận xét 1: TS Hồ Quang Như

TS Hồ Quang Như

Cán bộ chấm nhận xét 2: TS Nguyễn Hữu Lương

TS Nguyễn Hữu Lương

Luận văn Thạc sỹ được bảo vệ tại trường Đại học Bách Khoa − Đại học Quốc gia Tp

Hồ Chí Minh ngày 18 tháng 07 năm 2019

Thành phần hội đồng đánh giá Luận văn Thạc sỹ gồm:

1 GS TSKH Lưu Cẩm Lộc

2 TS Hồ Quang Như

3 TS Nguyễn Hữu Lương

4 TS Nguyễn Trí

5 TS Nguyễn Thành Duy Quang

Xác nhận của Chủ tịch Hội đồng đánh giá luận văn và Trưởng khoa quản lý chuyên ngành sau khi luận văn được sửa chữa (nếu có)

No: /BKĐT -

MASTER ENGINEERING THESIS PROJECT

MODIFIED FOR PROPYLENE PRODUCTION FROM ATMOSPHERIC RESIDUE

a Impregnating HZMS-5 with different Phosphorus precursors in order to improve the catalytic stability and hydrothermal stabilization, then examining additives activity under the severe FCC condition on Atmospheric residues from Crude Distillation Unit of Dung Quat Refinery impacted on Propylene yield

b Characterizing physicochemical properties of the modified additives by various methods: X-ray diffraction (XRD), X-ray fluorescence (XRF), Temperature Programmed Desorption (TPD) and Nitrogen Adsorption (BET)

The thesis was approved by the Division of Petroleum Processing

Ho Chi Minh City, July 18 th , 2019

DEAN OF FACULTY OF CHEMICAL ENGINEERING

Prof Dr Phan Thanh Son Nam

LE TRUNG NGHIA’S MASTER THESIS i

ACKNOWLEDGMENTS

First and foremost, I am grateful to my teachers Assoc Prof Dr Huynh Quyen and Dr Dao Thi Kim Thoa Completing this project is impossible without their support and guidance I would like to extend a special thanks to all my teachers from Division of Petroleum Processing Engineering as well as Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT or BKU)

Under the supervision of Vietnam Petroleum Institute (VPI) ’s experts, Dr Le Phuc Nguyen along with Dresden University of Technology (TUD) ’s teachers coming from Prof Dr Jan J Weigand’s group, especially Dr Oliver Busse and Ph

D Student Mario Suβ supported throughout my research period in Germany and Vietnam Petroleum Institute The valuable advice and support from my friends Mr Philipp Royla, Mr Cornelius Brand, Mr Pham Minh Tai, Mr Lars Dincklage and

Mr Tobias Schneider I would like to thank Dr Ho Quang Nhu and Dr Nguyen Thanh Duy Quang because of their valuable advice for the complete process of this thesis

Last, but not least, I would like to express my grateful honor to my family members and relatives who give me limitless love, encouragements in every milestone of my life

LE TRUNG NGHIA’S MASTER THESIS ii

TÓM TẮT

Công nghệ FCC được ứng dụng chủ yếu nhằm nâng cao hiệu suất xăng, tuy nhiên công nghệ này hoàn toàn có thể đảm đương nhiệm vụ sản xuất nguyên liệu cho công nghiệp hoá dầu, đặc biệt là propylene từ các phân đoạn dầu thô có giá trị thấp Việc này đem lại lợi nhuận tốt cho nhà máy thay vì nâng cao chất lượng xăng nhiên liệu trong khi các chính sách môi trường ngày càng khắt khe

Cải thiện quá trình suy giảm sản lượng propylene trong phân xưởng FCC thông qua việc sử dụng phụ gia ZSM-5 trên nền xúc tác FCC Tuy nhiên, độ bền và hoạt tính của phụ gia ZSM-5 dễ bị suy giảm trong điều kiện khắc nghiệt của phân xưởng FCC Việc biến tính phụ gia ZSM-5 bằng Photpho trên các tiền chất phổ biến riêng

ZSM-5 nhằm cải thiện độ bền thuỷ nhiệt và hoạt tính xúc tác

Đánh giá và so sánh hiệu quả biến tính của mỗi tiền chất phốt pho lên ZSM-5 như phụ gia của xúc tác phân xưởng FCC cho mục đích sản xuất propylene từ cặn của phân xưởng chưng cất khí quyển bằng phương pháp MAT, bên cạnh đó khảo sát một số yếu tố ảnh hưởng lên quá trình biến tính Photpho là nhiệm vụ của đề tài

LE TRUNG NGHIA’S MASTER THESIS iii

ABSTRACT

FCC technology has been applied to increase the gasoline yield in a refinery, but it can be produced petrochemical feedstocks properly such as propylene which plays an important role in plastic industry in the specific or petrochemical field in general Refinery gives a great economic profit from low-quality fractions of crude oil as the residue of CDU transforming to qualified petrochemical feedstocks Petrochemical feedstocks production compares to extremely high qualified gasoline production, whereas environmental commitments, regulations or sustainable policy have become rigorous so far, following the high-quality gasoline production on FCC

is improper development way at the current circumstances with the refinery

Adding ZSM-5 zeolite to FCC catalysts in FCCU improving propylene yield was proved in many types of research, but the hydrothermal stabilization and catalytic activity lifetime of ZSM-5 continue a problem which needs to be considered so far Phosphorus sources which take from two common phosphorus precursors include DAP and acid phosphoric separately modified ZSM-5 zeolite to solve the hydrothermal stabilization problem

Phosphorus precursors impact on ZSM-5 additive characteristics on FCC catalyst was investigated on the transformation of residue from crude oil distillation unit to fluid catalytic cracking unit for propylene production checking by MAT technology Besides, the influences of conditions on ZSM-5 zeolite structure in

methods

LE TRUNG NGHIA’S MASTER THESIS iv

PROTESTATION

I hereby certify that this study belongs to my own This research was conducted in cooperation between Ho Chi Minh City University of Technology (HCMUT or Bach Khoa University, Vietnam), Dresden University of Technology (TUD, Germany) and Petro Vietnam Institute (VPI, Vietnam) within the scope of the research program relying on financial aid of Germany government ASA project Both the laboratory of TUD (Inorganic Molecular Chemistry Department) under Prof Jan

J Weigand and Dr Oliver Busse’s permission and the laboratory of VPI under Dr

Le Phuc Nguyen’s permission supplied equipment as well as facilities for this study

All the contents of this research came from my real experiences and all the references were listed and cited If there is any fraudulent part in this study, I will take all responsibilities

Research author

Le Trung Nghia

LE TRUNG NGHIA’S MASTER THESIS v

CONTENTS

ACKNOWLEDGMENTS i

TÓM TẮT ii

ABSTRACT iii

PROTESTATION iv

CONTENTS v

LIST OF ABBREVIATIONS ix

LIST OF FIGURES xi

LIST OF SCHEMES xiv

LIST OF TABLES xv

CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW 1

1.1 Propylene production technology review 1

Demand 1

Propylene production and application 1

1.2 Zeolite applications 3

Fluid Catalytic Cracking technology overview 3

Fluid Catalytic Cracking catalysts 6

ZSM-5 additives in FCC catalysts 7

Point Zero Charge of ZSM-5 additive 14

Phosphorus modification affects ZSM-5 additives 15

Atmospheric residue processing for propylene production 19

1.3 The mechanism from the intake of feedstocks to propylene 22

1.4 Phosphorus post-modification of ZSM-5 26

Method of Phosphorus on additive ZSM-5 zeolite 26

LE TRUNG NGHIA’S MASTER THESIS vi

Accessibility and porosity 28

The decrease in acid sites strength 29

Aluminum phosphate formation 31

Thermal treatment 32

Phosphorus framework formation and incorporation with Zeolite Y 33

Improved catalytic stability 35

The reversible decrease in acid sites after steaming 36

CHAPTER 2 EXPERIMENTS 37

2.1 Material 37

2.2 Tools and equipment 37

2.3 ZSM-5 modification procedure 37

The preparation of H-form ZSM-5 37

Wet impregnation by Phosphorus precursors 39

Wet impregnation by Diammonium Hydro phosphate precursor 42

The deactivation of Phosphorus modified ZSM-5 additives 42

2.4 CATALYST EVALUATION METHOD 43

Catalyst preparation 43

Catalyst properties testing 44

2.4.2.1X-ray fluorescence (XRF) 44

2.4.2.2X-ray Diffraction (XRD) 45

2.4.2.3Brunauer–Emmett–Teller method (BET) 46

2.4.2.4Temperature Programmed Desorption-Ammonia (TPD-NH3) 47

Catalyst activity testing 54

2.4.3.1Micro activity test (MAT) 54

LE TRUNG NGHIA’S MASTER THESIS vii

2.4.3.2Micro activity test procedure (MAT) 55

Characterization of product contribution 56

2.4.4.1Gas Chromatograph analysis system (GC) 56

2.4.4.2Gas Chromatograph procedure (GC) 56

2.4.4.3Calculation of products distribution 57

CHAPTER 3 RESULTS AND DISCUSSION 58

3.1 Catalyst properties testing 58

XRD 58

XRF 59

TPD-NH3 60

3.2 Activity testing result 61

The influence of precursors solution concentration 61

The influence of P/Al ratio on the pore system of ZSM-5 additive 64

The influence stirring time step of impregnation time on the micropore 68

The influence of different precursors on the stabilization 69

The influence of different precursors on the Gasoline yield 71

The influence of different precursors on LCO and HCO yield 72

The influence of difference precursors on the Propylene yield 73

The correlation between Propylene yield and Gasoline output 77

The influence of the precursor on the acid activity 80

The influence of the precursor on the Conversion 83

The influence of Phosphorus modification on Coke yield 85

The qualitative evaluation of the effects of Phosphorus precursor 86

LE TRUNG NGHIA’S MASTER THESIS viii

CHAPTER 4 CONCLUSION AND RECOMMENDATION 88

4.1 Conclusion 88

4.2 Future perspectives 89

REFERENCES 90

APPENDIX 108

LE TRUNG NGHIA’S MASTER THESIS ix

LIST OF ABBREVIATIONS

LE TRUNG NGHIA’S MASTER THESIS x

Phosphoric before steam

Phosphoric after steam

hydrogen phosphate before steam

hydrogen phosphate after steam

phosphate at the mole ratio Phosphorus per Aluminum equal to 1

ratio Phosphorus per Aluminum equal to 1

LE TRUNG NGHIA’S MASTER THESIS xi

LIST OF FIGURES

Figure 1-1: The propylene supply and demand 2

Figure 1-2: Schematic depiction of the typical fluid catalytic cracking FCCU 5

Figure 1-3: Schematic representation of FCC catalysts 6

Figure 1-4: Incorporated FCC catalyst production process 6

Figure 1-5: Mechanism of coke formation for several reactant molecules 7

Figure 1-6: Effect of ZSM-5 contents on propylene yield by wt.% 8

Figure 1-7: Molecular traffic control in the Straight elliptical and Zig-zag circular channels of ZSM-5 zeolite 9

Figure 1-8: Channel structures of ZSM-5 and ZSM-11 10

Figure 1-9: MFI Channels 10

Figure 1-10: Schematic of the intergrowth structure of a ZSM-5 crystal and the relative pore orientations 11

Figure 1-11: Kinetic diameters for (a) propane and (b) propylene 12

Figure 1-12: Schematic representation of the dimensions of ZSM-5 zeolite 12

Figure 1-13: TPD of ammonia trace and acidity of phosphate modified hierarchical porous ZSM-5 catalysts (SiO2 /Al2O3 =360) 13

Figure 1-14: Schematic presentation of the surface polarization of an oxide particle as a function of the solution pH 14

Figure 1-15: C3–C4 selectivity and ratios of interest in the cracking of gasoil 16

Figure 1-16: Effect of ZSM-5 addition on products yields of gasoline and C3, C4 = 17

Figure 1-17: Effect of phosphorus and post-steam treatment on the cracking of n-hexane 18

Figure 1-18: Oil refinery process units 19

Figure 1-19: Schematic representation of the hierarchical pore structure in zeolite 20

Figure 1-20: Processing units in a fuel refinery 21

Figure 1-21: FCC reactions pathways to produce olefins 22

LE TRUNG NGHIA’S MASTER THESIS xii

Figure 1-22: Gasoline turning into a gas by FCC catalyst with Zeolite additive 23

Figure 1-23: Relative amount of Brønsted acid sites vs P/Al ratio 29

Figure 1-24: Relative concentration of acid sites (%) versus P/Al ratio 30

Figure 1-25: Model of the interaction of H3PO4 with Brønsted acid sites 31

Figure 1-26: Model was proposed for the interaction of Phosphorus with Brønsted acid sites of ZSM-5 31

Figure 1-27: Brønsted and Lewis acid sites in zeolites 33

Figure 1-28: Proposed model of different stages of dealumination occurs in the presence of phosphorus 36

Figure 2-1: The preparation of H-form ZSM-5 38

Figure 2-2: Wet impregnation 40

Figure 2-3: Both pH paper method and electronic pH calibration were applied to check the pH value in impregnation steps and adjusting pH value 41

Figure 2-4: Modified ZSM-5 additive was steamed at 1500 Kelvin (816°C) for 20 hours before the MAT test 42

Figure 2-5: Additives characterization protocols 44

Figure 2-5: The X-ray fluorescence process 45

Figure 2-6: A standard XRD pattern of MFI-group zeolite 45

Figure 2-7: XRD pattern of fully crystalline MFI, Si/Al = 12 to 13.5 46

Figure 2-8: AMI—902 (Altamira) TPD-NH3 analysis equipment 47

Figure 2-9: TPD spectrum of ammonia desorbing from H-ZSM-5, Volume desorption short by V des 48

Figure 2-10: The TPD-NH3 peaks of ammonia trace and acidity of phosphate modified samples 49

Figure 2-11: ZSM-5 P1, ZSM-5 P2, ZSM-5 P5, ZSM-5 P8 represented for 1%, 2%, 5%, 8% P on the Modified Samples, 673 K approximately 400°C 50

Figure 2-12: TPD-NH3 plots with total acidity, mmol NH3/g 50

LE TRUNG NGHIA’S MASTER THESIS xiii

thermally nontreated H-ZSM-5 51

Figure 2-14: TPD-profiles of parent and phosphorus modified H-ZSM-5 samples (P-content increases from top down) 52

Figure 2-15: Textural, structural and acidic properties of parent and phosphorus modified H-ZSM5 samples 52

Figure 2-16: Typical MAT equipment 54

Figure 2-17: MAT protocol and system 55

Figure 3-1: The XRD pattern of HZSM-5 impregnated with Phosphoric acid precursor without steam treatment 58

Figure 3-2: The XRD pattern of HZSM-5 impregnated with Phosphoric acid precursor after steam treatment 59

Figure 3-3: The characterization of acid property on catalysts by the TPD-NH3 method 60

Figure 3-4: Influence of various concentrations on Micropore area 61

Figure 3-5: Influence of various concentrations on external surface 63

Figure 3-6: Influence of P/Al ratio on t-Plot micropore area bst 64

Figure 3-7: Influence of P/Al ratio on t-Plot external surface area bst 65

Figure 3-8: MAT Conversion before steam (%) 66

Figure 3-9: MAT Conversion after steam (%) 67

Figure 3-10: MAT Conversion after steam (%) 68

Figure 3-11: Influence of P precursors on hydrothermal stability 69

Figure 3-12: Gasoline yield 71

Figure 3-13: Propylene yield 73

Figure 3-14: Propylene yield in order to make a comparison of stability 76

Figure 3-15: Total Gasoline, wt.% 77

Figure 3-16: The correlation between gasoline yield and propylene yield bst 79

Figure 3-17: The characterization of acid on catalysts by the TPD-NH3 method 80

Figure 3-18: Conversion of various treatment methods & P/Al ratios 83

Figure 3-19: Conversions at P/Al=1 84

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LIST OF SCHEMES

Scheme 1-1: Dominant pathways for FCC paraffin production 23 Scheme 1-2: Forming Propylene from Alkanes reaction 24 Scheme 1-3: Model proposed of the interaction between phosphorus

species and the Brønsted acid sites 33

LE TRUNG NGHIA’S MASTER THESIS xv

LIST OF TABLES

Table 1-1: Properties of major synthetic zeolites 4

Table 1-2: Landmark in the history of zeolites and related materials 9

Table 4-1: The influence of precursors on the external and micropore surface 70

Table 4-2: The LCO and HCO outputs 72

Table 4-3: The correlation between gasoline and propylene production bst 79

Table 4-4: Level of the acid sites per each testing samples 82

Table 4-5: Coke yield from testing samples 85

Table 4-6: Product distribution of several catalyst samples in activity testing 86

Table 4-7: The evaluation of catalyst samples treated with phosphorus 86

Table 4-8: The comparison of DAP and Phosphoric acid precursor on HZSM-5 87

LE TRUNG NGHIA’S MASTER THESIS 1

CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW

1.1 Propylene production technology review

Demand

There is a gradual rise of the light olefin consumption intensifying its production from current processes Moreover, annual Ethylene and Propylene production

in specific are important basic raw materials for the petrochemical industry, and the demand for light olefins such as ethylene and propylene consumption are increasing every year [5,6]

Besides, the high fatigue strength of components making by Polypropylene

Propylene production and application

The trend of some research in the recent year converts FCC feedstock to get

Petrochemical can get more benefits for non-fuel refinery products, while quality gasoline production is costly, and the electrical engine is also a new tendency

high-of automobile production Using catalytic additives and adjusting operating conditions Propylene has broad application in a global market (Polypropylene,

In fact, Propylene is producing in the catalytic processes only, and there are 3 technologies including Steam crackers or Pyrolysis which produce Propylene as an

Cracking, and Propane Dehydrogenation Giving details by latest statistic processes, Steam crackers provide about 60% of propylene, FCC units provide 30-35% and

Nevertheless, steam cracking needs high energy requirements and carbon dioxide emission, it boosted the Propylene production in Fluid Catalytic Cracking as

LE TRUNG NGHIA’S MASTER THESIS 2

contribution to meet the demand for propylene consumption, saving fossil fuel and lowing impacts of the greenhouse effect by cutting down exhaust fumes emission In the next ten years, the FCCU which is also an alternative method of Steam crackers produces even higher propylene yields

Optimizations can be acquired by changes in the reaction conditions, i.e raising riser temperature, residence time or the cat/oil-ratio, where total conversion is

accounts for 25 wt.% of FCC catalyst, the propylene yield is only 8.8 at C/O=2.3 and

Figure 1-1: The propylene supply and demand [4]

Figure 1-1 shows the propylene supply and demand for past summaries and the forecast from now until 2021, maximization of propylene production has become the focus of most refineries because it is in high demand and there is a supply shortage from modern steam crackers, which now produce relatively less propylene The flexibility of the fluid catalytic cracking (FCC) to various reaction conditions makes it possible as one of the means to close the gap between supply and demand,

LE TRUNG NGHIA’S MASTER THESIS 3

The world Propylene demand is bigger than the total of Propylene yield from both Steam Cracker and FCC method production route Although the gap can easily fill Propylene yield from steam cracker route which is not perfect with inflexibility operating conditions as well as high rate energy loss, so the FCC solution is potentially chosen by those later reasons

• Firstly, the use of lower activation energy for C-C bonds leads to the new naphtha cracking process is 150-250°C lower than those for steam crackers;

• Secondly, catalysts improve selectivity to the desired product as propylene for instance even in the same conditions as those of steam cracker, the olefin yield

is determined higher than all;

• Thirdly, the generator unit solves the coke formation on the surface of the catalysts;

• Fourth, the flexibility of the FCC is higher than a steam cracker

Additionally, the circulating fluidized bed is equipped by FCC technology, which has originally efficiency heat, mass transfer, and catalyst generation that go forward the upgrading of heavy feed to gasoline In term of olefin production, the remarkable principle has based on the interaction of feed and one or more crystalline microporous molecular sieves to selectively the feed into an olefin After excluding the energy content of final products, it is supported that Steam Cracker is also most of the energy-consuming process reached approximately about 8 % energy consumption of the

1.2 Zeolite applications

Fluid Catalytic Cracking technology overview

The main duty of FCC transforms the high-boiling feedstocks, a low-value fraction as residue from Atmospheric Distillation Column or Vacuum Distillation Column into the valuable product such as Gasoline, LPG, Diesel The catalytic cracking is more efficient in energy use and gives high yields of propylene and

LE TRUNG NGHIA’S MASTER THESIS 4

Under the severe regenerator condition in order to maintain the activity of catalysts for cracking heavy oils, the high hydrothermal stability is the important

by the post-synthesis treatments with Phosphorus, enhancing stability was anticipated along with the Propylene selectivity in term of Phosphorus impregnation

Catalysts for cracking heavy oils or atmospheric residue must have high hydrothermal stability in order to maintain activity under severe condition of regenerator and selectivity for light and high-valuable outputs’ production such as olefin, gasoline or diesel Steam catalytic cracking operating in the FCC mode could

Table 1-1: Properties of major synthetic zeolites [10]

Zeolite

Type

Pore Size Dimensions (Å)

Silica to Alumina Ratio

Applications

catalyst dewaxing, and methanol conversion

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Figure 1-2: Schematic depiction of the typical fluid catalytic cracking FCCU [12]

Figure 1-2 shows the schematic depiction of the typical fluid catalytic cracking

process, the recycling of catalyst is performed in the severe condition at the high

zeolite needs to be processed to improve the hydrothermal stabilization which is the

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Fluid Catalytic Cracking catalysts

Many components consist of zeolite, matrix, filler, and binder need to build a

Figure 1-3: Schematic representation of FCC catalysts [15]

Figure 1-4: Incorporated FCC catalyst production process [14]

Both the Figure 1-3 and Figure 1-4 point out the ZSM-5 belongs to part of FCC catalyst, whereas the positive benefits of Phosphorus modifying have been

ZSM-5 main role contributing cracking reaction, Binder is a substance added to the mixture to make all parts stick together Using in the combination with Ultra Stable

LE TRUNG NGHIA’S MASTER THESIS 7

Y Zeolite in FCC catalysts, ZSM-5 cracks low octane gasoline range material formed

important part in the first phase and synthesized ZSM-5 with various Si/Al ratio and its application to improve Motor octane number in my engineer thesis which plays an important role of this research

Figure 1-5: Mechanism of coke formation for several reactant molecules

Figure 1-5 shows the mechanism of coke formation for several reactant molecules such as Oligomerization (OL), hydrogen transfer (HT) and cyclization (Cyc) [18]

In the comparison, the possibility of Coke deposition on ZSM-5 is lower than zeolite Y due to its narrow pore which makes limitation of bulky coke One more evidence to prove that the ZSM-5 need to be added to the FCC catalysts instead of

ZSM-5 additives in FCC catalysts

When P-impregnated ZSM-5 sample is used as an additive for cracking

zeolites, especially ZSM-5 thanks the invention of Mobil Oil company, has used in

commercialization of ZSM-5 additive which plays a preferential cracking selectivity

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particular [9]

Figure 1-6: Effect of ZSM-5 contents on propylene yield by wt.% [4,9]

The figure 1-6 showed the effect of ZSM-5 contents on propylene yield by wt.%, supposing the ZSM-5 loading higher than 10% has no considerable increase of propylene, so it is not necessary the high existence of ZSM-5 in order to produce high propylene yield

There are many types of research using ZSM-5 which produces Propylene

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Table 1-2: Landmark in the history of zeolites and related materials [20]

Company

1983 First commercial use of ZSM-5 octane/ olefins additive

Mobil

Table 1-2 lists the timeline of ZSM-5 invention and olefins produce an application in reality

As figure 1-9 and figure 1-12, ZSM-5 and silicalite have two types of channels

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Figure 1-8: Channel structures of ZSM-5 and ZSM-11 [24]

prospects of Pentasil zeolite as ZSM-5 has never become obsolete relying on a variety

of applications The ratio of solid acidity over substrates affinity is widely available, especially; that of Silica per Aluminum can be freely controlled in a range of 6 to infinity In other words, the activity of the catalyst can be changed for specific reactions

Figure 1-9: MFI Channels [25]

Like Figure 1-9, the model of a porous system showed the way that the molecules connect together to become the porous system

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Figure 1-10: Schematic of the intergrowth structure of a ZSM-5 crystal and the

relative pore orientations [26]

Figure 1-10 shows the crystal structure of typical ZSM-5, the major activity and selectivity effects are caused by the nature and content of the zeolites present The pore size and shape in a zeolite may affect the selectivity of a reaction in three ways [27]:

Firstly, reactant selectivity occurs when the aperture size of the zeolite is such

it admits only certain smaller molecules and excludes larger molecules; hence, in a mixture, effectively only the smaller molecules react;

Secondly, product selectivity occurs when bulkier product molecules cannot diffuse out, and, it formed, they are converted to smaller molecules or to carbonaceous deposits within the pore These eventually may cause pore blockage;

insufficient space was available in the pores for two molecules of the dialkyl benzene

to come together This type of behavior is sometimes also termed restricted

transition-state selectivity Unlike reactant or product selectivity, spaciospecific;

The most important declaration in some previous research, shape selectivity may also be achieved or increased by partially blocking pore mouths, and a considerable number of patents have proposed the use of compounds of phosphorous

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Propylene’s slightly smaller kinetic diameter compared to propane, allows it to pass

Figure 1-11: Kinetic diameters for (a) propane and (b) propylene [31]

According to figure 1-11, the kinetic diameters makes the selectivity of propylene on ZSM-5 zeolites higher than propane

Figure 1-12: Schematic representation of the dimensions of ZSM-5 zeolite [33]

Macroscopic shape and the microscopic internal surface of ZSM-5 is depicted

in Figure 1-12 The interaction between phosphorus and zeolite Y [34], and especially ZSM-5, the density of the weak Brønsted acid sites was found to increase after treatment with phosphoric acid, the energy of activation increased with the increasing

LE TRUNG NGHIA’S MASTER THESIS 13

and subsequently a smaller yield of saturated aliphatics and aromatics than the parent

Phosphorus treatment was found to decrease the concentration of the strong Brønsted acids sites (bridging hydroxyl groups) by dealumination, The concentration of weak

the heavier components such as heavy fuel oil This is not surprising, because the pores in ZSM-5 are only 5–6 Å wide, which is not large enough for these large molecules to enter The main effects of adding ZSM-5 are an increase in the gasoline octane rating, a decrease in gasoline (typically C5–C12 hydrocarbons) and an

In accordance with other studies, decrease the concentration of the strong

Figure 1-13: TPD of ammonia trace and acidity of phosphate modified hierarchical

porous ZSM-5 catalysts (SiO 2 /Al 2 O 3 =360) [39]

LE TRUNG NGHIA’S MASTER THESIS 14

Figure 1-13 pointed out as much as Phosphorus loading, the lower strong acid sites retaining in the ZSM-5 lattice For zeolite Y, it was found that phosphorus added

forming different surface aluminophosphates that change the acid properties of the

bridged OH groups, decreasing zeolite acidity and, consequently, catalytic activity

framework dealumination and formation of aluminum phosphate; however, Seo et al

reduction of Brönsted acidity to the formation of octahedral aluminum through its

Point Zero Charge of ZSM-5 additive

Figure 1-14: Schematic presentation of the surface polarization of an oxide particle

as a function of the solution pH [44]

Based on the theory describing by Figure 1-14, the Point Zero Charge of Zeolite

experiences procedure was designed depending on this hypothesis supposed to strengthen the gradient mass transfer of Phosphorus from precursors to the zeolite lattice by maintaining pH of precursor lower than the ZPC of HZSM-5 in the impregnating step In the other words, the acid property of precursors solutions is

LE TRUNG NGHIA’S MASTER THESIS 15

Phosphorus modification affects ZSM-5 additives

Firstly, phosphorus impregnation on HZSM-5 additive was explored that only increases the hydrothermal stability of framework aluminum whatever the source of

The severe hydrothermal condition improvements substantially in the high olefin yield include Propylene and Ethylene and acid stability was investigated over

selectivity of HZSM-5 additives in part of FCC catalyst to Propylene was proven in various studies, but the enhancement of propylene selectivity with increasing phosphorus content was attributed to the reduction of strong acid sites on the H-ZSM-

5 [50] owing to lowering catalytic ability

However, meeting the high Propylene output need some main factors such as

0.5-0.7 in term of Si/Al=25, which this ratio especially similar to HZSM-5 applied in this

LE TRUNG NGHIA’S MASTER THESIS 16

Figure 1-15: C3–C4 selectivity and ratios of interest in the cracking of gas oil

Figure 1-15 shows the higher Conversion in the reaction to the higher propylene yield In the range of C3–C4 selectivity and ratios of interest in the

base catalyst and (⚫) 25-ZSM-5-St and () 25-ZSM5-1PSt at 750 ◦C for 5 h at 13.3

• 25-ZSM-5-St represented for (original ZSM-5 with Si/Al=25, Steam

treatment)

• 25-ZSM5-1PSt represented for (ZSM-5 with Si/Al=25, 1 wt.% P content, Steamed treatment)

For instance, in a previous study, the Propylene yield has reached a maximum

at 25 wt.% on Nigerian vacuum gas oil feedstock

LE TRUNG NGHIA’S MASTER THESIS 17

Figure 1-16: Effect of ZSM-5 addition on products

yields of gasoline and C 3 , C 4 = [17]

Figure 1-16 shows that the high ZSM-5 loading in FCC catalyst is not able to get more C3, whereas the gasoline yields get unexpected output Where:

At the nearly constant conversion of Gas Oil feedstock, the comparison of base Rare Earth Ultra Stable Y and 25 wt.% ZSM-5 additive in term of Light Olefins and Gasoline yields was illustrated in the inventory on 5.4 wt.% and 8.4% in the order given The presence of 25 wt.% ZSM-5 additive, there was no substantial shifts in bottoms (or HCO, Heavy Cycle Oil) and LCO (Light Cycle Oil) at constant

because Phosphate modification leads to pore blockage can change the shape

Regarding of the production schedule of Binh Son refinery about maintaining the Gasoline productivity currently, the amount of Phosphorus modification ZSM-5 additive was set at 3% in the total mass of FCC testing sample instead of 25 % in the previous studies

LE TRUNG NGHIA’S MASTER THESIS 18

One feature needs to consider that the ZSM-5 additive has no significant

In comparison to the literature review was declared that the optimum in both Activity and Hydrothermal stabilization is around 0.5 with the n-Decane cracking

Figure 1-17: Effect of phosphorus and post-steam treatment on

the cracking of n-hexane [60]

Figure 1-17 shows the optimum point which reaches the highest hydrothermal stabilization obtains relying on the control of P/Al ratio Effect of phosphorus and

• (red) = H-ZSM-5 (Si/Al=13);

• (green) = H-ZSM-5 steamed at 800°C for 5 hours;

• (blue) = H-ZSM-5 steamed at 800°C for 20 hours;

LE TRUNG NGHIA’S MASTER THESIS 19

• (Violet) = H-ZSM-5 (Si/Al=25) steamed at 750°C for 5 hours The reaction

Atmospheric residue processing for propylene production

Using catalyst ZSM-5 modified by phosphorus handling the Atmospheric

Figure 1-18: Oil refinery process units [62]

The feeding flow for each unit in the refinery was depicted in Figure 1-18 Oil refinery process units: upgrading processes for top-of-the-barrel cuts – VGO and

LE TRUNG NGHIA’S MASTER THESIS 20

lighter – boiling below about 1050°F (556°C) Almost all processes generate off gas (represented by red arrows) Off gases are collected, purified, and separated into components in refinery gas plants Usually, there are two gas plants, one for saturated streams and another for streams containing olefins HTU = hydrotreating unit, FCC

= fluid catalytic cracking unit, Alkyl = alkylation unit, Isom = isomerization unit,

Figure 1-19: Schematic representation of the hierarchical

pore structure in zeolite [9]

The transformation from Residue into LPG is depicted in Figure 1-19 Originally, the FCCU producing main cracking gasoline product has played a new important role: to increase the yield of propylene and other olefins This can be achieved by changing operational conditions and for instance, adjust higher reaction temperature and decreasing riser contact time Raising reaction temperature is not a good method for saving-energy target and the equipment lifespan But higher reaction temperature means impacts on the zeolite stabilization factors as well as catalyst circulation, so the catalyst modification aspect needs to be taken Y Zeolite integrating with ZSM-5 as an additive has strongly boosted Propylene production

LE TRUNG NGHIA’S MASTER THESIS 21

Figure 1-20: Processing units in a fuel refinery [38]

Either Vacuum Gasoil or residue is used as a feedstock for the FCC The figure below shows some of the major processing units commonly found in gasoline-oriented refineries The units shown in the dashed outline are less common Crude oil

is distilled into fractions that are processed in various units downstream The C3–C4 stream may be used directly as LPG, which is considered a type of clean fuel The C6–C10 naphtha is fed through a reformer that converts low octane naphthenes and paraffins into high-octane aromatics The vacuum gas oil (roughly C25–C40), is fed

to the FCC unit, where it is cracked to smaller molecules The straight run C3–C4 stream and the C3–C4 byproducts from reforming or hydroprocessing units are largely paraffinic The FCC is the major producer of olefins in the refinery, with a smaller contribution from thermal cracking processes like coking Most FCC units have an alkylation unit downstream to make premium alkylate fuel from the C3–C4 olefins, and isobutane In an FCC unit, the powdered catalyst continuously circulates between a riser-type reactor and a regenerator The base FCC catalyst is a stabilized

Y zeolite, bound in a spray-dried matrix such as silica–alumina Liquid feed is introduced at the base of the riser, where is vaporized by the red-hot catalyst The oil vapors sweep the catalyst up a tall reactor tube, while the cracking reaction goes on

At the top of the riser, the catalyst is separated out with cyclones, stripped with steam, and flows to the regenerator, where coke is burned off the catalyst The reaction products are sent through an elaborate train of distillation towers to separate them into useful fractions Usually, the C2− stream is used as fuel gas The C2− contains a

LE TRUNG NGHIA’S MASTER THESIS 22

significant amount of ethylene, but it is a challenge to recover the ethylene economically The yield of gasoline is around 50% by weight Our main interest here

is the C3–C4 stream, which can be used for making clean fuels The propylene is also

1.3 The mechanism from the intake of feedstocks to propylene

Limited the rate hydro transfer reaction which promotes the olefin hydrogenation makes the olefins regeneration or increased rate of hydrogen transfer

transfer activity as low as possible which tailors by the based-Y-zeolite catalysts of FCCU prevents the coke formation The recommendation to increase light olefins yield in the FCC process is adding ZSM-5 zeolite as additive Besides, not only adding ZSM-5 zeolite additive but also these methods: Using ZSM-5 with optimized Si/Al (low acidity), hydrothermally deactivated ZSM-5, treatment with phosphorus

[16]

Figure 1-21: FCC reactions pathways to produce olefins [64]

Figure 1-21 shows the ZSM-5 contribution for boosting C3,4,5= yield in the FCC unit, and the naphtha olefins yield is in the inversely proportional to olefin output