(255d) Bioethanol: Synthesis from Biomass and Catalytic Reforming for Hydrogen Production | AIChE

(255d) Bioethanol: Synthesis from Biomass and Catalytic Reforming for Hydrogen Production

Authors 

Duma, V. - Presenter, Abengoa Bioenergy R&D, Inc.


The talk presents the activities and projects of the company Abengoa Bioenergy in the areas of ethanol production, biomass conversion to bioethanol by fermentation or gasification and catalytic synthesis, and bioethanol reforming for production of hydrogen.

Residual biomass is underutilized at present. Promising potential uses are to ferment the cellulose fraction directly to ethanol or to gasify the entire biomass and use the resulting syngas, after cleaning and conditioning, for bioethanol synthesis. These applications would produce a versatile chemical and fuel, bioethanol, which is already accepted and integrated in the transportation infrastructure.

The objective for the gasification stage is to produce a synthesis gas which fulfils the requirements for chemical synthesis. Different combinations of gasification technology and gas cleaning processes are available. The choice is both a problem of technical performance and economical considerations. In case of agricultural and forestry residues, collection, transportation and feeding in the gasification system adds to the factors which need to be taken into account.

After proper cleaning and conditioning, the syngas can be used for catalytic synthesis of different fuels. It is our consideration that the synthesis of ethanol, ought to its remarkable properties, is a highly desirable goal. Unfortunately, in contrast to other fuels like methanol or Fischer-Tropsch hydrocarbons, there are no suitable catalysts for ethanol synthesis from syngas. It is for these reasons that our company has a multifaceted program in place aimed at developing a catalyst for ethanol synthesis. Our projects in this direction reach from basic studies aimed at a fundamental understanding of the chemical reaction mechanisms and kinetics involved in this process to synthesis experiments using real syngas from biomass gasification.

Bioethanol can be used directly as a fuel, neat or mixed with gasoline or diesel, or as a chemical for further processing. Another possibility is to use bioethanol as a source of hydrogen to power a fuel cell.

One of our projects has resulted in the development of a novel, patented catalyst for ethanol reforming to hydrogen. The catalyst, consisting of supported transition metal oxides, is inexpensive and has shown a very good performance which will be detailed. After reforming, the hydrogen-rich gas has to be conditioned to the specifications of the fuel cell system. In case of a proton exchange membrane (PEM) fuel cell, very low levels of carbon monoxide (CO) have to be attained. For this, the reformate gas undergoes a water-gas shift reaction, followed by selective CO oxidation or eventually membrane separation. In our present project, PEM fuel cells with power levels between 1 and 300 kW are tested with the hydrogen resulting from bioethanol reforming. The complex based on bioethanol reforming and fuel cell conversion can be used as a stationary or mobile energy generation system.