Production of High Value Liquid Fuels from Biomass Syngas

In the recent years we have seen violent fluctuations in the oil price. Furthermore there is now a widespread consensus that the anthropogenic emission of CO2 to a significant extent is contributing to the increase in global temperature.

Background

A solution that potentially addresses both these problems could be an increased use of liquid fuels derived from biomass in the transportation sector. Here the main interest is in fuels derived from so-called second generation sources like wood, straw etc.

A promising route for converting biomass into liquid transportation fuels is a gasification of the biomass by reaction with steam at high temperature and pressure. The gasification process produces so-called syngas – a mixture of CO and H2. The syngas formed in the gasification process can be converted into fuel chemicals in a variety of catalytic processes. Possible fuel chemicals include methanol, synthetic gasoline or diesel, dimethyl ether (DME) or a mixture of methanol and higher alcohols (HA). An important benefit of the gasification route to liquid transportation fuels compared to for example fermentation of biomass is the ability to co-process various feedstocks like biomass, coal and waste. This provides the process with an excellent flexibility towards for instance seasonal variations in biomass availability.

Alcohols such as methanol have high octane numbers and are therefore good additives to or replacements for oil derived gasoline. However the lower alcohols, and especially methanol, suffer from a limited miscibility with gasoline. This makes it difficult to phase-in the fuel use of alcohols like methanol on a large scale. A good solution might therefore be to use a mixture of methanol and higher alcohols, which, if the fraction of higher alcohols is sufficient, does not have these miscibility problems in gasoline/alcohol blends. Such a mixture of methanol and higher alcohols can be synthesized directly from syngas by means of, for example, alkali promoted sulfides of molybdenum and cobalt-molybdenum.

This synthesis of higher alcohols is the focus of the present project. The main challenge for the alcohol synthesis, which must be surmounted before the process can be commercialized, is that the amount of hydrocarbon by-products formed in the synthesis must be reduced.

Objective

The current project seeks to improve both stages in the production of higher alcohols from biomass, namely the thermal gasification of the biomass and the catalytic synthesis of the higher alcohols. The project will enhance the competitiveness of the participating company (Haldor Topsoe A/S) and contribute to the accumulation of knowledge within the Danish energy sector regarding the utilization of biomass for production of liquid fuels, heat and electricity. The project runs through 2008, 2009 and 2010 and has two main focus areas:

  1. Experimental and theoretical studies of the gasification of biomass and coal with the main focus on the composition of the formed syngas and the parameters affecting the syngas composition. This includes the development of a detailed mathematical model that is able to describe the gasification process. The model will be utilized to identify the optimal conditions for the gasification process.

  2. Development and experimental examinations of improved catalysts for the synthesis of higher alcohols from syngas. The main objective in these studies is to decrease the formation of hydrocarbon by-products, while optimizing the alcohol productivity. The optimization will also seek to identify the optimal process conditions for the alcohol synthesis.




Articles in journals with peer review

Qin,K., Lin,W., Fæster, S., Jensen,P.A., Wu,H., Jensen, A.D. ’Characterization of Residual Particulates from Biomass Entrained Flow Gasification’, Energy & Fuels, 2013, 26, pp. 262-270.

Qin, K., Jensen, P.A., Lin, W., Jensen, A.D. ‘Biomass Gasification Behavior in an Entrained Flow Reactor: Gas Product Distribution and Soot Formation’ Energy & Fuels, 2012, 26 , pp. 5992-6002.

Qin, K., Lin, W., Jensen, P.A., Jensen, A.D. ’High-temperature entrained flow gasification of biomass’, Fuel, 2012, 93, pp. 589–600. 

Christensen, J.M., Duchstein, L.D.L., Wagner, J.B., Jensen, P.A., Temel, B. and Jensen, A.D. ‘Catalytic Conversion of Syngas into Higher Alcohols over Carbide Catalysts’, Ind. Eng. Chem. Res., 2012, 51, pp. 4161−4172.

Christensen, J.M., Jensen, P.A., Schiødt, N.C. and Jensen, A.D. ‘Coupling of Alcohols over Alkali-Promoted Cobalt-Molybdenum Sulfide’, ChemCatChem, 2010, 2, pp. 523-526.

Christensen, J.M., Mortensen, P.M., Trane, R., Jensen, P.A. and Jensen, A.D. ’Effects of H2S and process conditions in the synthesis of mixed alcohols from syngas over alkali promoted cobalt molybdenum sulfide’, Applied Catalysis A: General, 2009, 366, pp. 29 43. 

Christensen, J. M., Mortensen, P. M., Trane, R., Jensen, P. A., Jensen, A. D., Synthesis of mixed alcohols over alkali promoted cobalt molybdenum sulfide, in preparation.

Articles in journals without peer review

Christensen, J. M, Jensen, P. A., Jensen, A.D., Effektivitet og CO2-fortrængning for syntese af flydende brændsler fra biomasse I. De mulige synteseveje, Dansk kemi, 10, 10-12, 2008.

Christensen, J. M, Jensen, P. A., Jensen, A.D., Effektivitet og CO2-fortrængning for syntese af flydende brændsler fra biomasse II. Sammenligning af syntesemulighederne, Dansk kemi, 11, 28-31, 2008.

Conference contributions

Poster at the14th International Congress of Catalysis in Seoul (13-18 July 2007): ”Catalytic conversion of syngas to mixed long chain alcohols, What is the effect of feed sulfur upon the alcohol synthesis over Alkali/Co/MoS2 catalysts”.

Contact

Anker Degn Jensen
Professor
DTU Chemical Engineering
+4545 25 28 41