Propane dehydrogenation(PDH)is one of the most effective technologies to produce propene.Non-noble zinc-based catalysts have paid increasing attention because of low cost and nontoxic,compared with industrial Pt and C...Propane dehydrogenation(PDH)is one of the most effective technologies to produce propene.Non-noble zinc-based catalysts have paid increasing attention because of low cost and nontoxic,compared with industrial Pt and Cr-based catalysts.However,they often suffer from limited catalytic activity and poor stability.Here,we introduced moderate Ni into ZnO supported Silicalite-1 zeolite to increase catalytic activity and stability simultaneously.Zn^(2+) was the definite active site and NiZn alloy facilitated the sluggish H recombination into H_(2)via reverse spillover.Furthermore,the introduction of Ni increased Lewis acid strength caused by electron transfer from ZnO to NiZn alloy,contributing to improved stability.For resulted 0.5 NiZn/S-1,propene formation rate was 0.18 mol C_(3)H_(6)·(g Zn)^(-1)·h^(-1) at 550℃,which was above 1.5 times higher than that over Zn/S-1 without Ni.Under stability test,the deactivation of0.5 NiZn/S-1 was 0.019 h^(-1),which was only 1/10 of that over Zn/S-1.展开更多
The effects of radiofrequency(RF)heating on the activity,structure,and surface hydrophobicity of mushroom polyphenol oxidase(PPO)were examined and four kinetic models of inactivation(First-order model,Weibull model,Lo...The effects of radiofrequency(RF)heating on the activity,structure,and surface hydrophobicity of mushroom polyphenol oxidase(PPO)were examined and four kinetic models of inactivation(First-order model,Weibull model,Logistic model and Bi-phasic model)were fitted.The results demonstrated that RF heating could effectively inactivate PPO,logistic and Bi-phasic model attained the best fit.The circular dichroism(CD)and fluorescence spectroscopy spectra revealed that RF heating at 65℃ for 180 s caused changes in the secondary and tertiary structures of PPO,reducing the α-helix content from 38.5% to 30.3% and red-shifting the emission peak wavelength of the maximum fluorescence intensity from 318 nm to 321 nm.RF heating also caused a significant enhancement of the surface hydrophobicity of the PPO(P<0.05).The color test results showed that RF heating could inhibit the browning of mushrooms(P<0.05).Thus,RF heating is an effective technique for the inactivation of enzymes and further research should be performed on RF heating applications to inactivate enzymes in the food industry.展开更多
基金Financial supports by the National Natural Science Foundation of China(22025802)the Haihe Laboratory of Sustainable Chemical Transformations(CYZC202101)。
文摘Propane dehydrogenation(PDH)is one of the most effective technologies to produce propene.Non-noble zinc-based catalysts have paid increasing attention because of low cost and nontoxic,compared with industrial Pt and Cr-based catalysts.However,they often suffer from limited catalytic activity and poor stability.Here,we introduced moderate Ni into ZnO supported Silicalite-1 zeolite to increase catalytic activity and stability simultaneously.Zn^(2+) was the definite active site and NiZn alloy facilitated the sluggish H recombination into H_(2)via reverse spillover.Furthermore,the introduction of Ni increased Lewis acid strength caused by electron transfer from ZnO to NiZn alloy,contributing to improved stability.For resulted 0.5 NiZn/S-1,propene formation rate was 0.18 mol C_(3)H_(6)·(g Zn)^(-1)·h^(-1) at 550℃,which was above 1.5 times higher than that over Zn/S-1 without Ni.Under stability test,the deactivation of0.5 NiZn/S-1 was 0.019 h^(-1),which was only 1/10 of that over Zn/S-1.
基金financially supported by the National Key R&D Program Subproject of China(2017YFD0401203-01).
文摘The effects of radiofrequency(RF)heating on the activity,structure,and surface hydrophobicity of mushroom polyphenol oxidase(PPO)were examined and four kinetic models of inactivation(First-order model,Weibull model,Logistic model and Bi-phasic model)were fitted.The results demonstrated that RF heating could effectively inactivate PPO,logistic and Bi-phasic model attained the best fit.The circular dichroism(CD)and fluorescence spectroscopy spectra revealed that RF heating at 65℃ for 180 s caused changes in the secondary and tertiary structures of PPO,reducing the α-helix content from 38.5% to 30.3% and red-shifting the emission peak wavelength of the maximum fluorescence intensity from 318 nm to 321 nm.RF heating also caused a significant enhancement of the surface hydrophobicity of the PPO(P<0.05).The color test results showed that RF heating could inhibit the browning of mushrooms(P<0.05).Thus,RF heating is an effective technique for the inactivation of enzymes and further research should be performed on RF heating applications to inactivate enzymes in the food industry.
