Microkinetic modeling and analysis of ethanol partial oxidation and reforming reaction pathways on platinum at short contact times

Numerical Investigation of the Effects of Coke on Transport Properties in an Oxidative Fuel Cell Reformer

Experimental investigations on the technical viability of solid oxide fuel cells to replace internal combustion engines in automobiles have increased in recent years. However, the performance and stability of catalysts in the presence of carbon is key for the commercial success of fuel cell reformers. In this paper, finite element method was used to study the effect of coke deposition on heat and mass transfer during the catalytic partial oxidation of ethanol in a packed bed reactor. The properties of Ni/Al₂O₃ catalyst bed were investigated after being subjected to several hours of carbon buildup. Bed permeability, porosity, and temperature distribution were significantly affected after just 1500 s of reaction time. It was observed that void fraction and permeability became nonuniform across the bed. These two parameters decreased with axial position, and the difference became more pronounced with time. A decrease in bed porosity reduced the bed temperature due to an increase in effective thermal conductivity and ethanol conversion and hydrogen selectivity decreased as a result. Thus, it was concluded that heat transfer becomes a limiting factor in reforming reactions in the presence of carbon. Production distribution before deactivation was also studied, and it was observed that a maximum ethanol conversion of 100% was achieved at 600 °C and a C/O ratio of 1.0. Finally, results from the reactions were compared to that of a different study to validate the reaction mechanism and similar results were found in the literature.

Recent advances in membrane reactors for hydrogen production by steam reforming of ethanol as a renewable resource

During the last decade, hydrogen has attracted lots of interest due to its potential as an energy carrier. Ethanol is one of the renewable resources that can be considered as a sustainable candidate for hydrogen generation. In this regard, producing hydrogen from ethanol steam reforming (ESR) would be an environmentally friendly process. Commonly, ESR is performed in packed bed reactors; however, this process needs several stages for hydrogen separation with desired purity. Recently, the concept of a membrane reactor, an attractive device integrating catalytic reactions and separation processes in a single unit, has allowed obtaining a smaller reactor volume, higher conversion degrees, and higher hydrogen yield in comparison to conventional reactors. This paper deals with recent advances in ESR in terms of catalyst utilization and the fundamental of membranes. The main part of this paper discusses the performance of different membrane reactor configurations, mainly packed bed membrane reactors, fluidized bed membrane reactors, and micro-membrane reactors. In addition, a short overview is given about the impact of ESR via different catalysts such as noble metal, non-noble metal, and bi-metallic catalysts.

Progress on sorption-enhanced reaction process for hydrogen production

Concerns about the environment and fossil fuel depletion led to the concept of “hydrogen economy”, where hydrogen is used as an energy carrier. Nowadays, hydrogen is mostly produced from fossil fuel resources by natural gas reforming, coal gasification, as well as the water-gas-shift (WGS) reaction involved in these processes. Alternatively, bioethanol, glucose, glycerol, bio-oil, and other renewable biomass-derived feedstocks can also be employed for hydrogen production via steam reforming process. The combination of steam reforming and/or WGS reaction with