In this work the effects of the contents of nickel （5, 7.5, 10 wt%） and copper （0, 1, 2 wt%） and reac- tion temperature （650, 700, 750 ℃） on the catalytic performance of Ni-Cu/Al_2O_3 catalyst in methane dry re...In this work the effects of the contents of nickel （5, 7.5, 10 wt%） and copper （0, 1, 2 wt%） and reac- tion temperature （650, 700, 750 ℃） on the catalytic performance of Ni-Cu/Al_2O_3 catalyst in methane dry reforming were evaluated using Box-Behnken design in order to optimize methane conversion, H_2/CO ratio and the catalyst deactivation. Different catalysts were prepared by co-impregnation method and characterized by XRD, BET, H_2-TPR, FESEM and TG/DTA analyses. The results revealed that copper addi- tion improved the catalyst reducibility. Promoted catalyst with low amounts of Cu gave higher activity and stability with high resistance to coke deposition and agglomeration of active phase especially during the reaction. However catalysts with high amounts of Cu were less active and rather deactivated due to the active sites sintering as well as Ni covering by Cu-enriched phase. The optimal conditions were de- termined by desirability function approach as 10 wt% of Ni, 0.83 wt% of Cu at 750℃. CH_4 conversion of 95.1%, H_2/CO ratio of 1 and deactivation of 1.4% were obtained experimentally under optimum conditions, which were in close agreement with the values oredicted hv the developed model.展开更多
Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In o...Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.展开更多
With the vacuum freeze-drying technology, frozen dumpling wrappers were prepared, to investigate the effects of six kinds of food additives, including modified starch, compound phosphate, maltodextrin, guar gum, disti...With the vacuum freeze-drying technology, frozen dumpling wrappers were prepared, to investigate the effects of six kinds of food additives, including modified starch, compound phosphate, maltodextrin, guar gum, distilled monoglycerides and transglutaminase （TG enzyme）, on the drying rate, rehydration ratio and sense value of the frozen dumpling wrappers. The results showed that, with respective addition of 6% modified starch, O. 1% compound phosphate, 10% maltodextrin, 0.4% guar gum, 0.4% distilled monoglyceride and 0.3% transglutaminase, the drying rate, rehydration ratio and sense value of the frozen dumpling wrappers were the highest.展开更多
文摘In this work the effects of the contents of nickel （5, 7.5, 10 wt%） and copper （0, 1, 2 wt%） and reac- tion temperature （650, 700, 750 ℃） on the catalytic performance of Ni-Cu/Al_2O_3 catalyst in methane dry reforming were evaluated using Box-Behnken design in order to optimize methane conversion, H_2/CO ratio and the catalyst deactivation. Different catalysts were prepared by co-impregnation method and characterized by XRD, BET, H_2-TPR, FESEM and TG/DTA analyses. The results revealed that copper addi- tion improved the catalyst reducibility. Promoted catalyst with low amounts of Cu gave higher activity and stability with high resistance to coke deposition and agglomeration of active phase especially during the reaction. However catalysts with high amounts of Cu were less active and rather deactivated due to the active sites sintering as well as Ni covering by Cu-enriched phase. The optimal conditions were de- termined by desirability function approach as 10 wt% of Ni, 0.83 wt% of Cu at 750℃. CH_4 conversion of 95.1%, H_2/CO ratio of 1 and deactivation of 1.4% were obtained experimentally under optimum conditions, which were in close agreement with the values oredicted hv the developed model.
基金grateful for the financial support from the National Key Research and Development Program of China(Grant Nos.2017YFB0307901 and 2017YFE0102500)。
文摘Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.
基金Supported by National Undergraduate Training Program for Innovation and Entrepreneurship(201410459011)
文摘With the vacuum freeze-drying technology, frozen dumpling wrappers were prepared, to investigate the effects of six kinds of food additives, including modified starch, compound phosphate, maltodextrin, guar gum, distilled monoglycerides and transglutaminase （TG enzyme）, on the drying rate, rehydration ratio and sense value of the frozen dumpling wrappers. The results showed that, with respective addition of 6% modified starch, O. 1% compound phosphate, 10% maltodextrin, 0.4% guar gum, 0.4% distilled monoglyceride and 0.3% transglutaminase, the drying rate, rehydration ratio and sense value of the frozen dumpling wrappers were the highest.
