Thermochemical pretreatment

Stirred tanks are typically used for the thermochemical pretreatment. To simulate flow of corn stover slurries in stirred tanks, the rheologic properties of these suspensions must be known. The corn stover slurries in stirred tank reactors typically range from 10 to 40% solids (3). 

Conversion efficiency and robust fermentation of mixed-sugar lignocellulose-derived hydrolysates are critical for producing ethanol at low cost to realize a commercially viable biorefinery. Biomass sugars are typically released by thermochemical pretreatment followed by enzymatic hydrolysis of chopped or milled biomass. The pretreated soluble fraction of biomass is called the hydrolysate and the hydrolysate containing the insoluble... 

Raw biomass is extremely persistent to enzymatic degradation. Therefore, methods of thermochemical pretreatment have been developed to improve the digestibility of biomass (18). For example, ammonia explosion, aqueous ammonia recycle, controlled pH, dilute acid, flow through, and hme treatment were applied to prepare com stover, i.e., the leaves and stalks of maize, for a subsequent conversion to sugars. 

The search for new and cheap substrates for the production of bioenergy and other biotechnological products is continuously demanded. Pal et al. reported that the mustard stalk and straw served as an alternative substrate for the production of lignocellulolytic enzymes and as a source for saccharification. The biomass from halophyte plants such as Retama retam and Juncus maritimus were used as the substrate for bioethanol production. The combined effect of thermochemical pretreatment and enzymatic hydrolysis of kitchen wastes for maximizing the production of fermentable soluble sugars has been described previously. ... 

Thermochemical treatment, such as with steam and dilute sulfuric acid, is a popular pretreatment process. This treatment opens the lignocellulosic pore structure and increases the susceptibility of biomass to enzymatic attack (2). This pretreatment step effectively hydrolyzes the biomass,... 

Ionic liquids have only just begun to be investigated for biomass related processes within the last 10 years, yet there are already many exciting examples of how they can be applied in this area. They have been used in cellulose functionalisation, thermochemical depolymerisation, enzymatic depolymerisation, extraction of biomass components, and biomass pretreatment processes. In a growing number of cases, ionic liquid processes have been patented, which suggests future commercial value. 

It is necessary to acknowledge that some existing experimental data indicates that oxygen can be removed from Li/MgO directly during the reduction in hydrogen at temperatures as low as 873 K (see, for instance, Leveies, 2002). Such discrepancies with the data described above might be due to some difference in catalyst preparation/pretreatment procedures, which leads to the formation of active sites with somewhat different thermochemical characteristics. What is important is to attribute the evaluated kinetic parameters to the catalysts of particular thermochemistry. 

M/US-Ex (1 wt% M, M=Ir,Ru, Si Al=95) was prepared as follows. US-Ex obtained by thermochemical treatment of NH Y and subsequent extraction of the non-framework aluminium species with dilute hydrochloric acid [29] was treated with aqueous solutions of [Ir(NH2)jCl](Cl)2 and RuCl +NH Cl, respectively. The samples were dried at 383 K for 3 h and calcined in air at 533 K for 3 h. The structure of the zeolite, checked by IR spectroscopy using the KBr wafer technique, was not changed by the pretreatment and the adsorption experiments. 

E. Chornetr R.P. Overend and co-workers at the Universite de Sherbrooke have been working on a liquefaction process in pressurized solvent for some years. Their approach involves an overall integration of biomass pretreatment, fractionation, acid processing, thermochemical and biochemical treatment. 

A biorefinery is the integral upstream, midstream, and downstream processing of biomass into a range of produas. In the classification system lEA Bioenergy Task 42 (described in the next chapter) has differentiated between mechanical pretreatments (extraction, fractionation, separation), thermochemical conversions, chemical conversions, enzymatic conversions, and microbial (fermentation both aerobic, anaerobic) conversions. 

Garg A., Mishra I.M., Chand S. Thermochemical precipitation as a pretreatment step for the chemical oxygen demand and color removal from pulp and paper mill effluent. Ind. Eng. Chem. Res., 2005 44(7) 2016-2026. 

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