A post-synthesis modification method, named ion etching, is proposed to adjust the morphology of titanium silicalite TS-1 for a better catalytic activity. The new method mainly involves treating titanium silicalite TS...A post-synthesis modification method, named ion etching, is proposed to adjust the morphology of titanium silicalite TS-1 for a better catalytic activity. The new method mainly involves treating titanium silicalite TS-1 with an ammonia-containing aqueous solution in autoclave under the conditions of ca. ammonia aqueous solution concentration 0.5-14 mol/L NH 3, volume ratio of liquid/solid 20-100, hydrothermal temperature 100-180 ℃ and contact time 24-500 h. According to the characterizations by SEM, XRF, XRD, FTIR and UV-Vis, the modification can transform a well-defined large crystal TS-1[1 μm×2 μm×6 μm, n(Si)/n(Ti)=53.62] into fine grains which can avoid falling off from the matrix if the conditions of the treatment are properly controlled. The effect of ion etching upon TS-1 morphology is attributed to the OH - ion(derives from NH 3·H 2O) catalyzed hydrolysis of the T-O-T bridge bond of the silicic zeolitic framework. Its main advantages over mechanical ball-millingthe conventional zeolitic morphology modification method, include actually fully retained crystallinity and almost intact coordination state of the active Ti sites of the remained framework, as confirmed by XRD, FTIR and UV-Vis. Probe reaction shows that, the large crystal TS-1 modified by the present method at 170 ℃ for 129 h, when used as the catalyst for epoxidation of propylene, could be operated at propylene weight hourly space velocity of 0.5 h -1, and 97.85% hydrogen peroxide conversion and 96.87% propylene oxide selectivity were obtained. However, to reach comparative hydrogen peroxide conversion, the intact zeolite could only be operated under propylene weight hourly space velocity of 0.2 h -1. The remarkable increase of the catalytic activity of the modified TS-1 may be attributed to the improved intra-crystal diffusivity and the excellent preservation of the crystallinity and active Ti sites by the present modification.展开更多
The effect of emulsification pretreatment on the acidic protease catalyzed hydrolysis of corn glu- ten reed(CGM)has been studied.Results show that under the hydrolysis conditions of acidic protease/sub- strate ratio o...The effect of emulsification pretreatment on the acidic protease catalyzed hydrolysis of corn glu- ten reed(CGM)has been studied.Results show that under the hydrolysis conditions of acidic protease/sub- strate ratio of 10%(g/g),CGM substrate concentration of 80 g/L and reaction temperature of 55℃,the di- rect hydrolysis of CGM by the acidic protease for 24 h gave a protein extraction rate of 62.79 % and a hydrol- ysate containing 45% oligo-peptides of molecular weight below 1000 u .By subjecting CGM under high- speed emulsification pretreatment at 7 000 r/min for 1 h,the hydrolysis of the resulted CGM fine particle un- der the same conditions gave a proptein extraction rate of 88.47% and a hydrolysate containing 78% oligo- peptides of molecular weight below 1000 u.The composition analysis of the hydrolysate on HPLC indicates that the emulsification pretreatment also increased the content of branch-chain amino acids in hydrolysate. That is to say,the emulsification pretreatment is useful for the preparation of high F ration oligo-peptides from CGM.展开更多
文摘A post-synthesis modification method, named ion etching, is proposed to adjust the morphology of titanium silicalite TS-1 for a better catalytic activity. The new method mainly involves treating titanium silicalite TS-1 with an ammonia-containing aqueous solution in autoclave under the conditions of ca. ammonia aqueous solution concentration 0.5-14 mol/L NH 3, volume ratio of liquid/solid 20-100, hydrothermal temperature 100-180 ℃ and contact time 24-500 h. According to the characterizations by SEM, XRF, XRD, FTIR and UV-Vis, the modification can transform a well-defined large crystal TS-1[1 μm×2 μm×6 μm, n(Si)/n(Ti)=53.62] into fine grains which can avoid falling off from the matrix if the conditions of the treatment are properly controlled. The effect of ion etching upon TS-1 morphology is attributed to the OH - ion(derives from NH 3·H 2O) catalyzed hydrolysis of the T-O-T bridge bond of the silicic zeolitic framework. Its main advantages over mechanical ball-millingthe conventional zeolitic morphology modification method, include actually fully retained crystallinity and almost intact coordination state of the active Ti sites of the remained framework, as confirmed by XRD, FTIR and UV-Vis. Probe reaction shows that, the large crystal TS-1 modified by the present method at 170 ℃ for 129 h, when used as the catalyst for epoxidation of propylene, could be operated at propylene weight hourly space velocity of 0.5 h -1, and 97.85% hydrogen peroxide conversion and 96.87% propylene oxide selectivity were obtained. However, to reach comparative hydrogen peroxide conversion, the intact zeolite could only be operated under propylene weight hourly space velocity of 0.2 h -1. The remarkable increase of the catalytic activity of the modified TS-1 may be attributed to the improved intra-crystal diffusivity and the excellent preservation of the crystallinity and active Ti sites by the present modification.
文摘The effect of emulsification pretreatment on the acidic protease catalyzed hydrolysis of corn glu- ten reed(CGM)has been studied.Results show that under the hydrolysis conditions of acidic protease/sub- strate ratio of 10%(g/g),CGM substrate concentration of 80 g/L and reaction temperature of 55℃,the di- rect hydrolysis of CGM by the acidic protease for 24 h gave a protein extraction rate of 62.79 % and a hydrol- ysate containing 45% oligo-peptides of molecular weight below 1000 u .By subjecting CGM under high- speed emulsification pretreatment at 7 000 r/min for 1 h,the hydrolysis of the resulted CGM fine particle un- der the same conditions gave a proptein extraction rate of 88.47% and a hydrolysate containing 78% oligo- peptides of molecular weight below 1000 u.The composition analysis of the hydrolysate on HPLC indicates that the emulsification pretreatment also increased the content of branch-chain amino acids in hydrolysate. That is to say,the emulsification pretreatment is useful for the preparation of high F ration oligo-peptides from CGM.
