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Pine as a softwood and poplar as a hardwood pretreated with hydrochloric acid (HCl), phosphoric acid (H3PO4), and hypophosphorous acid (H3PO2) are studied for the pyrolytic properties and products in thermogravimetry (TG) and fixed bed reactor. The pyrolysis performances are pronouncedly distinguished due to the compositional and structural changes induced by the acid pretreatments. Reduction in the mineral content in the biomass feedstocks by pretreatment with the acids results in significant changes in the pyrolytic products. The residual P in the H3PO2-pretreated biomass apparently catalyzed the biomass deeper dehydration in pyrolysis compared to the other two mineral acids. TG analysis shows a shift of the temperature of maximum mass loss (Tmax) by more than 40 &deg, C to lower temperature in the decomposition of the H3PO2-pretreated biomass from that of the untreated and the HCl- and H3PO4-pretreated biomass. Inspired by the striking differences in TG profiles of biomass pretreated by the three acids, thermal pyrolysis of pretreated biomass was carried out in a fixed bed reactor aimed at producing biochemicals at low temperatures (330 &deg, C and 400 &deg, C). The liquid products obtained from the fixed bed reactor show remarkably different major anhydrosugars as a result of pretreatment by the three acids. While phenolics dominate in the collected pyrolysis liquid from untreated biomass samples, biomass pretreated with all three acids results in substantially reduced phenolics in the bio-oils. The reduction in phenolic compounds in the bio-oil may be attributed to the reduction in mineral content in the feedstock. Consequently, the yields of anhydrosugars, mainly levoglucosan (LG) and levoglucosenone (LGO) are increased. LG yields of 20.9&ndash, 28.5% from the cellulose content are obtained from HCl- and H3PO4-pretreated pine/poplar, with very low LGO yield (less than 1.7%). However, H3PO2-pretreated biomass is selective to produce LGO, especially at 330 &deg, C. LGO yields of 7.4% and 6.7% are obtained from H3PO2-pretreated pine and poplar, respectively.

Developing economically viable cellulosic ethanol process requires concentrated fermentable sugars and minimum water consumption. Biorefinery economics requires highly integrated efficiencies in the full utilization of all biomass components. Toward this objective, we have developed an enzyme-free mechanocatalytic saccharification process that combines mix-milling of P2O5 with lignocelluloses and successive hydrolysis into fermentable sugars. Demonstrated with corn stover (CS) and CS-xylose residues, after recovery of valuable hemicellulose, fermentable glucose in 75% yield at a high biomass loading (92 mg/mL) was obtained with concomitant precipitation of pristine lignin. The undetoxified concentrated hydrolysate allows for fermentative upgrading, achieving 42 g/L ethanol (a benchmark (40g/L) for an economically feasible bioethanol process) in 52 h after hemicellulose is converted into xylose. P2O5 is essential in fragmentation of cellulose in the milling stage and subsequent accelerated hydrolysis to gl...

A acetyl-substituted tetrahydrobenzofuran, 1-(4,5,6,7-tetrahydro-1-benzofuran-6-yl)ethenone (6-AcBZOF) and a acetyl-substituted tetrahydronaphthalene, 1-(1,2,3,4-tetrahydronaphthalen-2-yl)ethenone (2-AcTNAPH) were conveniently synthesized from renewable furanics by cascade Diels–Alder and dehydration reactions. The Diels-Alder cycloaddition of 4-(2-Furyl)-3-buten-2-one (4-FB) with ethylene followed by dehydration in presence of zeolites was studied. Sn grafted Beta zeolite exhibited high performance with 69% yield of 2-AcTNAPH starting from 4-FB. In this reaction, 6-AcBZOF was produced as intermediate. Further, it was found that this acetyl-substituted tetrahydrobenzofuran could be formed in high yield, 86%, in the absence of catalyst. For the first time in the literature, we report the synthesis of a renewable acetyl-substituted tetrahydronaphthalene in high yield from biomass-derived 4-FB in a tandem approach. While a acetyl-substituted tetrahydrobenzofuran could be prepared without a catalyst, catalyst was essential for the successful synthesis of the acetyl-substituted tetrahydronaphthalene.

Fatty acids are the primary natural starting materials for the production of surfactant and detergent molecules. Derived from vegetable (oil) and animal (fat) triglyceride sources, the fatty acids are linear aliphatic carboxylic acids. Industrial interest in branched-chain fatty acids is driven by the needs for products with enhanced performance benefits including higher solubility, ease of handling, better hard water tolerance, and improved oxidative stability. Therefore, catalytic processes have been developed for the conversion of linear fatty acids to branched ones. High yields of branched acids are obtained from unsaturated fatty acids over acidic zeolites, particularly those with large pores. Fatty esters also are readily isomerized to branched ones by means of the same catalyst and process. It is postulated that the isomerization of fatty acids proceeds through three- and four-membered ring carbocation intermediates formed inside the largepore zeolites. This is supported by evidence of methyl and ethyl branching in the primary and final products. The total number of carbon atoms in the fatty acid molecule is unchanged. Surfactants derived from branched fatty acids show favorable physical properties, including a lower viscosity and improved handling, even as intended performance characteristics are maintained.