Development of Pt-Zn/Al2o3 Catalyst for N-Octane Reforming.
ABSTRACT
Six different platinum and zinc gamma-alumina-supported catalysts were developed by the impregnation method. Five of the catalysts consist of 1.0% wt of Zn and varying amounts of Pt (0, 0.5, 1.0, 1.5, 2.0% wt) while the sixth catalyst was chlorinated gamma-alumina, having no active metal(s) serving as the control sample.
The catalysts were characterized using X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET), and scanning electron microscope (SEM) techniques.
The catalytic performances of these catalysts were evaluated with respect to n-octane reforming in a packed tubular reactor. The XRD patterns show that the chlorinated support (γ-Al2O3) is amorphous as its diffractogram was characterized by low-intensity counts and broad peaks.
The other catalysts had similar Bragg angles. The textural properties determined by the BET analyses were: specific surface area ranging from 44m2 /g to 78m2 /g, pore volume ranging from 0.02cm3 /g to 0.04cm3 /g, and pore size ranging from 2.00nm to 2.10nm.
The catalytic performances of the catalysts for n-octane reforming were determined at varying reactor temperatures (4300C, 4550C, 4800C, 5050C, and 5300C).
The results showed low reformate yield at low reactor temperatures (430-4550C) when the reactor was packed with the chlorinated gamma-alumina.
Nonetheless, a significant improvement in the reformate yield was observed at higher temperatures (T ≥ 4550C). When the Zn/Al2O catalyst was used, the reformate yield increases from a minimum of 46% at 4300C to a maximum of 83% at 5300C.
TABLE OF CONTENTS
Title Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i
Declaration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii
Dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vi
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
List of Plates . . . . . . . . . . . .. . . . . . . . . .. . . . . . .. . . . . . .. . . .. . . . . .. . . . . .. . . . .. . . . . . . . . . . xiv
List of Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .xv
Abbreviations and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . xvi
CHAPTER ONE: INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . … . . . . . . . . 1
1.1 Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Research Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.3 Aim and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.4 Scope of Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..4
1.5 Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
CHAPTER TWO: LITERATURE REVIEW
2.1 Catalysts and Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. ..6
2.1.1 Properties of a Good Catalyst . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.2 History of Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.1.3 Classification of Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
2.1.4 Catalyst Supports . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . ..10
2.1.5 Explanations of some used terms . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2.2 Chemistries of Platinum, Zinc and Alumina. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
2.2.1 Platinum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
2.2.2 Zinc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..15
2.2.3 Alumina .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . ..15
2.3 Essentials of Platinum-on-alumina Catalyst .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .17
2.3.1 Dispersion of Platinum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
2.4 Naphtha . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.1 Naphtha Production in the Refineries . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . .. . ..20
2.4.2 Properties of Naphtha . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.4.3 Uses of Naphtha . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .21
2.4.4 Reforming and Reformate . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . 23
2.5 Naphtha Reforming Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . .. . 25
2.5.1 Feedstocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . 26
2.5.2 Typical Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . 26
2.5.3 The Process Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 27
2.6 The Refinery CRU . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . 32
2.7 Preparation of Pt-Zn/Al2O3 Catalyst . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . .. . . .35
2.7.1 Description of the Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 36
2.8 Catalyst Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
2.8.1 Basic Principles of BET Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.8.2 Basic Principles of XRD Analysis . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .39
2.8.3 Basic Principles of SEM Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.8.4 Principles of GC-MS Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .41
CHAPTER THREE: MATERIALS, EQUIPMENT, AND METHODS
3.1 Materials . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . .43
3.2 Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
3.3 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . ..44
3.4 Experimental Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . ..44
3.4.1 Catalysts Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . .. . . . . . . . . . . . 45
3.4.2 Charaterization of the Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . .45
3.4.3 Catalysts‟ Performance Evaluations . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Catalysts Characterization . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.1.1 XRD Analysis . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 48
4.1.2 Catalysts‟ Textural Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
4.1.3 Catalysts‟ Surface Morphology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
4.2 Catalysts Performance Evaluations . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . …53
4.2.1 Component Identification Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
4.2.2 Effects of Catalyst Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
4.2.3 Selectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.2 Recommendations . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
INTRODUCTION
Gasoline is a complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, blended to form a fuel suitable for use in internal combustion engines (ICEs).
The ICEs became a far better alternative to the steam-propelled engines, used in antiquity, which is often bulky and relatively inconvenient. Gasoline consumption has increased globally since the advent of modern civilization, and the revolutionary growth in automobile industries.
In 2010 alone, the global consumption stood at about a 3498million liters per day (MLPD). Annually, the consumption increased by about 37MLPD, while the local consumption rate within Nigeria stood at about 31MLPD; valued at about 3billion Naira, (IES, 2013).
Gasoline is produced by blending several gasoline components, such as reformate (reformed naphtha), FCC gasoline, alkylate, and others. Catalytic reforming of heavy naphtha constitutes a very important source of products having high octane numbers which are key components in the production of gasoline.
Catalytic reforming is the process of transforming hydrocarbons with low octane numbers to aromatics and iso-paraffins which have high octane numbers. The catalytic reformer is one of the major units for gasoline production in the refineries.
It can produce 37 wt% of the total gasoline pool, while about 50% of the pool may come from the fluid catalytic cracker (FCC), (Kjell et al 2004). Other gasoline-producing units are alkylation and isomerization.
REFERENCES
Acres, J. K., Bird, A. J., Jenkins, J. W. and King F. (1999). The Design and Preparation of
Supported Catalysts. Cited on-line at www.studentsrepo.um.edu on Sept. 15, 2011, Pg 17.
Anne M. H., (1999). Catalysts. Cited from www. about.com. on October 18, 2011, 11:05PM, Pg 17.
API-American Petroleum Institute (1994). Research Project 65, Sixteenth Annual Report.
Ateş, S. (2011), Oxidation of ethanol and carbon monoxide on alumina-supported metal/metal
oxide xerogel catalysts; An MSc Thesis, Chem Eng Dept. Submitted to The Graduate School of
Engineering and Sciences of İzmir Institute of Technology.
Bartholomew, C. (2001). Journey of Applied Catalysis-Mechanism of catalyst deactivation;
Department of Chemical Eng, Brigham Young University, Provo, UT84602, USA. Pg 17-60.
Bawa, G. S. (2012). Development of gamma-alumina from Kankara Kaolin for potential
application as catalysts support. M.Sc Research Project. Chem. Eng. Dept, Ahmadu Bello
University, Zaria.
Bentor Yinon (2014). Chemical Element.com-Zinc. Cited online on July 11, 2014 by 7:00PM at
(www.chemicalelements.com/elements/zn.html).
Brunauer, S., Emmett, P. H. and Teller, E. (1938). Journal of Americal Chemical Society.
Vol 60, Pg 309.
Carl B. (2013); Catalytic reforming of C5 to C12 naphtha modeled through the kinetic modeling
toolkit: A B.Eng thesis submitted to the Engineering Faculty of the University of Delaware.
StudentsandScholarship Team.
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