Catalytic Process For Synthesis Research Articles

Exergy analysis of alternative configurations of biomass gasification-mixed alcohol production system via catalytic synthesis and fermentation

In-depth exergy analysis of three conceptual biomass-mixed alcohol systems using syngas platform has been studied, according to the distribution strategy of synthesis tail gas and syngas. The system configurations are base case, cascade case and parallel case. The results show that higher alcohol yield (C2+OH) is highest in base case, which is a catalytic synthesis process with synthesis tail gas recycling. Yet its exergy efficiency is lower than that of 43.8% in the hybrid conversion configuration of cascade case, of which synthesis tail gas is recycled to an additional subsystem for gas fermentation. And it has increased bioconversion of COX components (CO and CO2) in tail gas for ethanol production under moderate bioreaction condition and biomass carbon utilization ratio of 38.8% is obtained in cascade case. With the detailed exergy analysis at the levels of system, subsystem, and operation component, it highlights that the subsystems of gasification and steam & power generation contribute above 70% of total system exergy destruction, mainly from gasifier and combustor. The results of this study provide a further understanding towards bio-mixed alcohol production configuration to improve its thermodynamic performance as exergy efficiency via the hybrid conversion processes of catalytic synthesis and metabolic fermentation pathway.

Immobilization strategy of accessible transmission for trypsin to catalyze synthesis of dipeptide in mesoporous support

Immobilized trypsin in mesoporous silica foams was used to catalyze dipeptide synthesis in hydrophilic organic solvent instead of soluble form. The area surface of nano support was measured. The catalytic activity, coupled yield and kinetic characterization of immobilized trypsin were examined. Bz-Arg-OEt was chosen as the acyl donor with Lys-OH as the nucleophile. The trypsin-catalyzed synthesis condition was optimized, such as catalytic temperature, pH, reaction time, physical properties and content of organic solvents, together with the added enzyme amount. The immobilized trypsin showed 112.8% of residual activity with 91.9% of coupled yield, and the kinetic parameters exhibited accessibility for transmission. The product yield of 5.8% was reached at the optimum conditions for enzymatic synthesis of dipeptide: 800 mg of wet immobilized trypsin (200 mg/g support) was used in Tris-HCl buffer (0.1 mol/L, pH 8.0) containing 80% (v/v) ethanol solvents for 6 h of reaction time at 35 °C. This attempt of immobilized strategy for trypsin in nanopores renders the possibility of wide application of inorganic nano-sized support in catalytic synthesis process, which can avoid usage of large amounts of organic solvents in washing steps by chemical methods and reduce the tedious purification process of its soluble form.

A synthesis of mono-crystalline silicon nitride filaments

A catalytic process for synthesis of pure, mono-crystallineα-Si3N4 filaments, with iron particles of some micrometres in diameter as catalyst, was investigated. Silicon subhydrides, producedin situ by reaction of silicon powder with hydrogen at 1300° C, were used as the silicon source. Experiments with molecular nitrogen as the nitrogen source failed, but the use of ammonia was successful. At 1300° C mono-crystallineα-Si3N4 filaments up to some micrometres in diameter and some centimetres in length were successfully produced. These filaments exhibit tensile strength values between 30 and 50 GPa, and Young's modulus values between 550 and 750 GPa.

A Synthesis of Mono-Crystalline Silicon Nitride Filaments

A catalytic process for synthesis of pure, mono-crystallineα-Si3N4 filaments, with iron particles of some micrometres in diameter as catalyst, was investigated. Silicon subhydrides, producedin situ by reaction of silicon powder with hydrogen at 1300° C, were used as the silicon source. Experiments with molecular nitrogen as the nitrogen source failed, but the use of ammonia was successful. At 1300° C mono-crystallineα-Si3N4 filaments up to some micrometres in diameter and some centimetres in length were successfully produced. These filaments exhibit tensile strength values between 30 and 50 GPa, and Young's modulus values between 550 and 750 GPa.