Liquefaction of biomass

Thermochemical Liquefaction. Most of the research done since 1970 on the direct thermochemical liquefaction of biomass has been concentrated on the use of various pyrolytic techniques for the production of liquid fuels and fuel components (96,112,125,166,167). Some of the techniques investigated are entrained-flow pyrolysis, vacuum pyrolysis, rapid and flash pyrolysis, ultrafast pyrolysis in vortex reactors, fluid-bed pyrolysis, low temperature pyrolysis at long reaction times, and updraft fixed-bed pyrolysis. Other research has been done to develop low cost, upgrading methods to convert the complex mixtures formed on pyrolysis of biomass to high quality transportation fuels, and to study liquefaction at high pressures via solvolysis, steam—water treatment, catalytic hydrotreatment, and noncatalytic and catalytic treatment in aqueous systems. 

A similar strategy consists in the liquefaction of biomass with phenol under acidic conditions to obtain phenolic monomers. The type of monomers obtained vary greatly (Lin et al, 2001). These monomers can be reticulated with the help of temperature and formaldehyde to obtain novolac- or resol-type resins. 

It was concluded from this assessment that the most promising process for gasoline production by direct liquefaction of biomass is atmospheric flash pyrolysis. The high-pressure process may have the same future potential, but the uncertainties are much greater. 

Davis, H. G. (1983). Direct Liquefaction of Biomass Final Report and Summary of Effort 1977-1983, LBL-16243. Lawrence Berkeley Laboratory, University of California, Berkeley. 

Various catalysts were examined to increase the products obtained from thermochemical reaction of biomass. Appell and co-workers demonstrated that solid organic materials, including urban refuse, agricultural wastes, wood and bovine manure, can be converted directly to heavy fuel oil in the presence of a catalyst such as sodium carbonate. Since then, a great number of works have been reported on the direct liquefaction of biomass in the presence of suitable catalysts. Recent publication, the addition of Na2C03 greatly increased the reaction rate. Minowa et... 

For the conversion of biomass resources into useful chemicals and bio-ener, three major process types, direct combustion, gasification and liquefaction, are effective. Among them, liquefaction for liquid transpiration fuels is, in particular, important because it is difficult to replace them with other energy forms. Thus, a study of the liquefaction of biomass is of interest. ... 

Pyrolysis and liquefaction of biomass can be used to produce bio-oils, which are mixtures containing up to 400 compounds including acids, alcohols, aldehydes, esters, ketones and aromatic compounds [31, 42], Bio-oils can be used as boiler fuel or in chemical production. Pyrolysis occurs at 375-525 °C and 1-5 bar in the absence of oxygen. Liquefaction occurs at 250-325 °C and 50-200 bar [31]. 

Pacific Northwest Laboratory (PNL) and Lawrence Berkeley Laboratory (LBL) have been selected to provide program management services to the Biomass Energy Systems Program. PNL is responsible for the technical management of development activities directed toward the thermochemical conversion of biomass feedstocks by direct combustion, gasification and indirect liquefaction via synthesis gas. LBL is responsible for the technical management of development activities on the direct liquefaction of biomass feedstocks. 

Thermochemical liquefaction of biomass is basically a simple process whereby it is heated with alkali under pressure at temperatures up to 400 C. This simple procedure converts the biomass to a mixture of gas (2-10%), char (5-40%), and oil (up to 40%), on a weight basis. It is one of several methods available for conversion of biomass to potential liquid fuels, the others being direct heating of dry matter (destructive distillation, pyrolysis) (1), fermentation (or anaerobic digestion) ( ), and gasification (partial oxidation) ( ) followed by liquefaction to methanol. There are variants on all of thesb processes. 

In 1924, Waterman and Kortlandt ( ) observed that semicoke obtained from lignite was liquefied more rapidly if there was an overpressure of hydrogen and/or carbon monoxide. Fischer and Schrader ( ) observed that sodium formate in large amounts facilitated the liquefaction of various materials including peat and cellulose at 400 C. The effect of formate or carbon monoxide on the rate of biomass liquefaction was reported in 1960 by Appell, Wender, and Miller ( ) working at the Bureau of Mines in Pittsburgh. In a series of publications (36-40), these and other workers at the Bureau of Mines showed a definite effect of carbon monoxide on the alkaline liquefaction of biomass. 

Elliott, D. C. "Process Development for Direct Liquefaction of Biomass," Fuels from Biomass and Wastes Ann Arbor Science Publishers Ann Arbor, MI, 1981 pp. 435-450. 

In the early 1970 s, in response to the world oil crisis, studies on the direct thermal liquefaction of biomass were initiated. These studies could be classified into those on water-based processes and those on non-water-based processes. The focus in this chapter is on the water-based processes and, in particular, on a process which uses no catalysts or reducing gases. It should be noted that actual biomass used for commercial liquefaction would certainly contain significant moisture, and water is expected as a product of the liquefaction. Despite this, the water-based and non-water-based processes are significantly different. 

Variations in Product Due to Feedstock. While process-related differences in product composition have been evident, extensive study of the effect of feedstock on product composition has never been undertaken. Some limited comparative tests can be gleaned from the literature however, most process research in direct liquefaction of biomass has been performed with woods of various species. Table I provides some of the results available in the literature for non-woody feedstocks. Significant differences in heteroatom content are evident, but only limited chemical analysis is available in most cases. 

Davis, H., G. et al. "The Products of Direct Liquefaction of Biomass," in Fundamentals of Thermochemical Biomass Conversion. R. P. Overend, T. A. Milne, and L. K. Mudge, Eds Elsevier Applied Science Publishers, New York, 1985 p 1027. 

Tymchyshyn M, Xu CB (2010) Liquefaction of biomass in hot compressed water for the production of phenolic compounds. Bioresour Technol 101 2483... 

Koll, P., Bronstrup, P. and Metzger, J. O. (1983) Liquefaction of biomass witli supercritical fluids in high pressure/liigli temperature flow reactor in Chemical Engineering at Supercritical Conditions, Paulaitis, M.E., Penninger, J.M.L., Gray, R.D. Jr. and Davidson, P., Ed. Ann Arbor Science Ann Arbor, MI.. 

Liquefaction of biomass is mostly performed at low temperature and high pressure in presence of hydrogen and a catalyst. The process results in a liquid product along with considerable amount of tars which makes the process expensive for their removal. Autothermal reforming is an attractive alternative... 

Demirbas, A., 2008. Liquefaction of biomass using glycerol. Energy Sources, Part A 30,1120-1126. 

Elliott, D., et al., 1991. Developments in direct thermochemical liquefaction of biomass 1983-1990. Energy Fuels 5 (3), 399-410. 

Elliott, D.C., et al., 2015. Hydrothermal liquefaction of biomass developments from batch to continuous process. Bioresource Technology 178 (0), 147—156. 

Hydrothermal liquefaction of biomass and hydrotreating of the biocrude product. 

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