FUEL PROCESSING: MODELLING AND STRUCTURED CATALYTIC REACTORS

Energy consumption is the important component in the debates of global climate change and sustainable energy future. According to International Energy Agency, world energy consumption will rise by 56% from 2010 to 2050 with 80% share of fossil fuels resulting in increased emissions of greenhouse gases. Research & development is required to supply clean fuel, increase efficiency of energy utilization and eliminate pollutant emissions. Renewable energy (solar, wind etc.,) systems are important but their penetration in the vast existing energy system is slow, painful and highly uncertain. Hydrogen is the proposed solution to future energy availability, environmental challenges and developing new energy industry. Hydrogen is an energy carrier like electricity; can be produced from renewable and non-renewable energy resources (natural gas, petroleum, coal etc.,) through water electrolysis, reforming, gasification etc. Transition from fossil fuel based energy systems to hydrogen based energy systems involves significant scientific, technological and socioeconomic barriers. Hydrogen produced from fossil fuels through fuel processing can be used for stationary and mobile fuel cell based applications and additionally will help to develop hydrogen infrastructure due to its availability at acceptable cost from the existing wide network. Small scale natural gas and petroleum reformers and hydrogen purification technologies represent an important technology for hydrogen production to create hydrogen filling stations that will help for transition to larger hydrogen supply. The doctoral thesis is focused on: (1) modelling in Aspen plus to compare different standalone fuel processor and integrated with auxiliary power unit for syngas and electricity production; (2) preparation, characterization and testing of structured catalytic reactors (monoliths, foams and plate reactor) for methane steam reforming. Chapter 1 describes the introductory materials of fuel processing and structured catalytic reactors. In chapter 2, the performance of the CO preferential oxidation (PROX) process was compared with the CO selective methanation (SMET) one, both applied as the last clean-up process step of a fuel processor unit (FPU) to remove CO from syngas. The FPU was completed with the reformer (autothermal reformer ATR or steam reformer SR) and a non-isothermal water gas shift (NI-WGS) reactor. Furthermore, the reforming of different hydrocarbon fuels, among those most commonly found in service stations (gasoline, light diesel oil and compressed natural gas) was examined. The comparison, in terms of different FPU configurations and fuels, was carried out by a series of steady-state system simulations in Aspen Plus®. In chapter 3, the performances of four different auxiliary power unit (APU) schemes, based on a 5 kWe net proton exchange membrane fuel cell (PEM-FC) stack, are evaluated and compared. The fuel processor section of each APU is characterized by a reformer (autothermal ATR or steam SR), a non-isothermal water gas shift (NI-WGS) reactor and a final syngas catalytic clean-up step: the CO preferential oxidation (PROX) reactor or the CO selective methanation (SMET) one. Furthermore, three hydrocarbon fuels, the most commonly found in service stations (gasoline, light diesel oil and natural gas) are considered as primary fuels. The comparison is carried out examining the results obtained by a series of steady-state system simulations in Aspen Plus® of the four different APU schemes by varying the fed fuel. In chapter 4, performance of Ru/La-Al2O3 catalysts was evaluated over different structures monoliths and foams for methane steam reforming. Structures of different materials, cpsi/ppi were prepared and characterized with different loadings of 1.5%Ru/3%La-Al2O3 catalyst and tested to find optimum loading at S/C of 3.0 with different temperatures and weight hourly space velocity (WHSV). Preparation and characterization of catalyst coated structures were carried out in University of Basque Country, San Sebastian Spain and experimentations were performed in Politecnico di Torino, Italy. In chapter 5, catalyst (5%Pt/Al2O3) preparation, characterization and experimentations were performed to couple methane steam reforming and combustion on alternate side of catalyst (5%Pt/Al2O3) coated plate reactor. Preliminary experimentations were performed to find out the most active side to use for methane steam reforming. Then, performance of catalytic plate reactor was evaluated by coupling both reactions in co-current and counter-current flow arrangements.