ALMA MATER STUDIORUM – Università di Bologna FACOLTÀ DI CHIMICA INDUSTRIALE Dipartimento di Chimica Industriale e dei Materiali NEW CATALYST FOR THE H2 PRODUCTION BY WATER-GAS SHIFT REACTION PROCESSES Tesi di dottorato di ricerca in CHIMICA INDUSTRIALE (Settore CHIM/04) Presentata da Dr. Giuseppe BRENNA Relatore Coordinatore Prof. Angelo VACCARI Prof. Fabrizio CAVANI Correlatori Prof. Giuseppe FORNASARI Dr. Francesco BASILE ciclo XXIII Anno 2010 A me stesso Key words Copper and Iron as active phase Hydrogen Hydrotalcite Perovskite Water-gas shift reaction Abbreviations WGS – Water-Gas shift HDS – Hydrodesulphuration FT – Fischer-tropsch ATR – Auto-thermal reforming POX – Partial oxidation CPO – Catalytic partial oxidation SR – Steam reforming CO-PROX – CO preferential oxidation LTS – Low temperature shift MTS – Medium temperature shift HTS – High temperature shift GHSV - gas hourly space velocity DG – Dry gas PVK – Perovskite HT – Hydrotalcite SUMMARY 1 INTRODUCTION _______________________________________________________________ 1 1.1 HYDROGEN ___________________________________________________________________ 2 1.1.1 Industrial Applications ____________________________________________________ 4 1.1.1.1 Hydrotreating _________________________________________________________________ 5 1.1.1.2 Hydrocracking _________________________________________________________________ 6 1.1.1.3 Ammonia synthesis _____________________________________________________________ 6 1.1.1.4 Direct Reduction of Iron OreS (DRI) ________________________________________________ 8 1.1.1.5 Methanol Synthesis _____________________________________________________________ 8 1.1.1.6 Dimhetyl Ether Synthesis _______________________________________________________ 10 1.1.1.7 Fischer‐Tropsch synthesis (FTS) __________________________________________________ 12 1.1.2 Energy Carrier __________________________________________________________ 14 1.1.2.1 Fuel Cells ____________________________________________________________________ 14 1.1.3 Production Processes ____________________________________________________ 21 1.1.3.1 Catalytic Reforming ____________________________________________________________ 23 1.1.3.2 Dry Reforming ________________________________________________________________ 24 1.1.3.3 Steam Reforming (SR) and Water‐Gas Shift (WGS) ___________________________________ 24 1.1.3.4 Auto‐Thermal Reforming (ATR) ___________________________________________________ 27 1.1.3.5 Partial Oxidation (POX and CPO) __________________________________________________ 28 1.1.3.6 Biomass and Electrolysis ________________________________________________________ 31 2 THE WATER‐GAS SHIFT (WGS) REACTION ______________________________________________ 35 2.1 REACTION _____________________________________________________________________ 35 2.1.1 Thermodynamic __________________________________________________________ 35 2.1.2 Industrial Reactors ________________________________________________________ 37 2.1.3 Diffusional Effects and Pellet Size _____________________________________________ 39 2.1.4 Reaction Kinetics __________________________________________________________ 40 2.1.4.1 Mechanisms ____________________________________________________________________ 40 2.1.4.2 Rate Expressions ________________________________________________________________ 49 2.2 COMMERCIAL CATALYSTS __________________________________________________________ 53 2.2.1 High‐Temperature Shift (HTS) [Tin > 300°C] _____________________________________ 53 2.2.1.1 Preparation ____________________________________________________________________ 54 2.2.1.2 Formulation Improvement ________________________________________________________ 55 2.2.1.3 Reduction ______________________________________________________________________ 56 2.2.1.4 Deactivation and Poisoning ________________________________________________________ 58 2.2.2 Low‐Temperature Shift (LTS) [Tin ≈ 200 °C] ______________________________________ 59 2.2.2.1 Preparation ____________________________________________________________________ 63 2.2.2.2 Formulation Improvement ________________________________________________________ 65 2.2.2.3 Recent Development _____________________________________________________________ 66 2.2.2.4 Reduction ______________________________________________________________________ 67 2.2.2.5 Deactivation and Poisoning ________________________________________________________ 69 2.3 NEW GENERATION (MTS) CATALYSTS __________________________________________________ 70 2.3.1 Precious Metal‐Based Catalysts ______________________________________________ 70 2.3.2 Gold Catalysts ____________________________________________________________ 72 3 EXPERIMENTAL SESSION _______________________________________________________ 81 3.1. MATERIALS ________________________________________________________________ 81 3.1.1 Perovskite (PVK) ________________________________________________________ 81 3.1.2 Hydrotalcite (HT) ________________________________________________________ 82 3.2. CATALYST PREPARATION _____________________________________________________ 84 I 3.2. CATALYST PREPARATION _____________________________________________________ 84 3.2.1 Perovskite‐Type (PVK) Samples ____________________________________________ 84 3.2.2 Hydrotalcite‐Type (HT) Precursors __________________________________________ 85 3.3. CHARACTHERIZATION METHODS __________________________________________________ 86 3.3.1 X‐Ray Diffraction Analysis (XRD) ____________________________________________ 86 3.3.2 Temperature Programmed Analyses (TPR/O) _________________________________ 88 3.3.3 Surface Area and Porosimetry Analyses ______________________________________ 89 3.4. PLANT SPECIFICATIONS ________________________________________________________ 90 3.4.1 Catalyst Shape _________________________________________________________ 90 3.4.2 Reduction step _________________________________________________________ 91 3.4.2.1 Typical Reduction of HTS Catalysts ________________________________________________ 91 3.4.2.2 Typical Reduction of M/LTS Catalysts ______________________________________________ 92 3.4.3 Lab‐scale Pilot Plant _____________________________________________________ 93 3.4.4 Inert Material __________________________________________________________ 95 3.4.5 Activity Tests ___________________________________________________________ 96 3.5. QUALI‐QUANTITATIVE ANALYSIS __________________________________________________ 97 3.5.1 Gas Chromatography ____________________________________________________ 97 3.5.2 Data elaboration ________________________________________________________ 98 4 RESULTS AND DISCUSSION ____________________________________________________ 101 4.1. AIM OF THE WORK __________________________________________________________ 101 4.2. COMMERCIAL CATALYSTS _____________________________________________________ 101 4.2.1 Cu/Zn‐based Catalyst ___________________________________________________ 101 4.2.1.1 Activity _____________________________________________________________________ 104 4.2.1.2 Characterization after reaction __________________________________________________ 108 4.2.2 Pt/Re‐based Catalyst ___________________________________________________ 113 4.2.2.1 Activity _____________________________________________________________________ 115 4.2.2.2 Characterization after reaction __________________________________________________ 117 4.2.3 Comparison among the commercial catalysts ________________________________ 119 4.3. PEROVSKITE‐TYPE CATALYSTS ___________________________________________________ 121 4.3.1 PVK‐type samples ______________________________________________________ 121 4.3.1.1 Activity _____________________________________________________________________ 123 4.3.1.2 Characterization after reaction __________________________________________________ 125 4.3.2 Ce‐containing samples __________________________________________________ 131 4.3.2.1 Activity: effect of copper promoting ______________________________________________ 134 4.3.2.2 Characterization after reaction __________________________________________________ 135 4.3.3 Comparison among the perovskite samples _________________________________ 138 4.4. EX‐HT SAMPLES ___________________________________________________________ 140 4.4.1 Ex‐HT CATALYSTS ______________________________________________________ 140 4.4.1.1 effect of Cu‐Content on the activity ______________________________________________ 142 4.4.1.2 Characterization after reaction __________________________________________________ 146 4.4.2 Comparison among the ex‐HT catalysts _____________________________________ 150 4.5. STUDY OF THE DEACTIVATION PHENOMENA _________________________________________ 152 4.5.1 Model of the WGS Reactor _______________________________________________ 153 4.5.1.1 Procedure __________________________________________________________________ 154 4.5.1.2 Results _____________________________________________________________________ 155 5 CONCLUSIONS ______________________________________________________________ 159 ACKNOWLEDGMENTS ________________________________________________________________ 161 II 1 INTRODUCTION The total primary energy supply (TPES) is dominated by fossil fuels as energy sources and it amounted to about 87 % in 2008, with an oil contribution of 33 % (Fig. 1.1) (1). Moreover, oil is the most versatile of the fossil fuels, with high energy density and ease of transportation. However, in view of the limited reserves, a number of alternative fuels