In the paper, wheat straw was rapidly liquefied in the mild condition. The optimum liquefaction effect was obtained at steam-explosion pretreatment of wheat straw, liquefaction temperature of 140 degrees C, solvent/wheat straw ratio of 6: 1, glycol (EG):glycerol = 5, sulfuric acid of 5%, and wheat straw of water content of 150%. During the liquefaction, cellulose, semi-cellulose and lignin are decomposed, which results in changes of hydroxyl value, acid value, viscosity and weight-average molecular weight of the reaction system. The liquefaction product was used to prepare polyurethane foam. Compared with the normal PUF, the foam had similar mechanical properties and better water absorption and biodegradability. (c) 2007 Published by Elsevier Ltd on behalf of Taiwan Institute of Chemical Engineers.

A novel method of utilizing the biomass resource: Rapid liquefaction of wheat straw and preparation of biodegradable polyurethane foam (PUF)

Large amounts of organic solid waste are generated daily throughout the world. Hydrothermal processing has been shown to be a promising solution for dealing with this type of waste. This paper reviews the types of hydrothermal processing currently available, their advantages and disadvantages, and their suitability for converting organic solid wastes to value-added products. This technology can also be used to produce fuels such as bio-char, bio-oil, and biogas, which are more energy-dense than fuels produced after biochemical conversion of waste. Furthermore, hydrothermally produced fuels have similar energy densities to fossil fuels. Hydrothermal technology provides opportunities for resource recovery such as converting waste into value-added products (e.g., organic acids and fertilisers), nutrient recovery and metal removal from organic waste. The challenges associated with developing hydrothermal processing at an industrial scale are examined, and research perspectives and future developments are discussed in this article. Since the hydrothermal process is capable of eliminating and transforming organic waste efficiently, its customer readiness level (CRL) and societal readiness level (SRL) are moderate. However, this technology has a low technology readiness level (TRL) because it operates at high temperatures and pressures. Lack of fundamental thermodynamic data at extreme conditions, limited understanding of reaction kinetics and mass transfer effects on the process are the main challenges of hydrothermal processing. Other important factors of hydrothermal processing are its economic and safety considerations which must be considered before installing a hydrothermal processing unit. A commercial case study on hydrothermal technology (Terax™) revealed that the challenge of sewage sludge management can be addressed successfully using a combination of biological and hydrothermal processes.

Resource recovery from organic solid waste using hydrothermal processing: Opportunities and challenges

The conversion of biomass materials into oils has a precise objective: 
To transform a carbonaceous solid material which is originally difficult to handle, bulky and of low energy concentration, into pumpable oils having physico-chemical characteristics which permit storage, transferability through pumping systems, and further use either in direct combustion furnaces or as feedstocks for hydrotreatment leading to specific fuels and chemicals.

Biomass Liquefaction: An Overview

Renewable resources can provide a substantial energy resource for the United States. The direct production of liquid fuels from renewable resources, however, is limited to the use of biofuels. Liquids are preferred for use as transportation fuels because of their high energy density and handling ease and safety. Both biomass and municipal waste are being studied as the feedstock for production of liquid fuels [1]. Liquid fuel production from these feedstocks can be accomplished by several processes including hydrolysis and fermentation of the carbohydrates to alcohol fuels, thermal gasification and synthesis of alcohol or hydrocarbon fuels, direct extraction of biologically produced hydrocarbons such as seed oils or algae lipids, or direct thermochemical conversion of the biomass or municipal waste to liquids and catalytic upgrading to hydrocarbon fuels. This paper discusses direct thermochemical conversion to achieve biomass liquefaction.

Liquid hydrocarbon fuels from biomass

Direct liquefaction of different lignocellulosics and their constituents: 1. Fractionation, elemental composition

Conversion of cellulosic wastes to oil

Hydroliquefaction is a well-known technique for coal liquefaction. Work with carbon monoxide, however, showed unexpectedly high liquefaction activity and indicated that the presence of both hydrogen and carbon monoxide (as in synthesis gas) could lead to improved liquefaction, particularly for low rank coals. The objective of the work reported here was to develop a better understanding of the chemistry of liquefying coal with synthesis gas plus water and to assess the potential of such a process. The effects of changing gas composition, temperature, pressure, solvents, catalysts and coal types were studied to better understand the process fundamentals and to lay the groundwork for studies in continuous reactors on a larger scale. A variety of coals were converted in batch autoclaves to a low-sulfur fuel oil at temperature of 425 to 450/sup 0/ C and pressures of 2200 to 2400 psig, using 1:1 (H/sub 2/:CO) synthesis gas at reaction times of 30 to 60 minutes at temperature. Although early work suggested that lignites could be readily liquefied without added catalytic agents, later experiments showed that a greatly improved product could be obtained by adding pyrite, which is normally present only in small amounts. Pyrite or, in particular, its reduction product pyrrhotite,more » appear to be important catalysts for coal liquefaction, and, in general, the reactivity of coals correlates well with the pyrite (or iron plus sulfur) content. An important consideration is the optimum temperature for reacting carbon monoxide or its (catalytic) intermediates with coal. This temperature is below 400/sup 0/C, and it is necessary to allow for some reaction time between 380 and 400/sup 0/C. Finally, coal liquefaction with synthesis gas appears to be compatible with the type of processing used to produce Solvent Refined Coal or SRC-II.« less

R.D. Miller

Papers

Conversion of cellulosic wastes to oil

Coal liquefaction with synthesis gas