Theoretically predicted innovative palladium stripe dopingcobalt(111) surface with excellent catalytic performance for carbonmonoxide oxidative coupling to dimethyl oxalate

Pd-based catalysts are extensively employed to catalyze CO oxidative coupling to generate DMO,while the expensive price and high usage of Pd hinder its massive application in industrial production.Designing Pd-based catalysts with high efficiency and low Pd usage as well as expounding the catalytic mechanisms are significant for the reaction.In this study,we theoretically predict that Pd stripe doping Co(111)surface exhibits excellent performance than pure Pd(111),Pd monolayer supporting on Co(111)and Pd single atom doping Co(111)surface,and clearly expound the catalytic mechanisms through the density functional theory(DFT)calculation and micro-reaction kinetic model analysis.It is obtained that the favorable reaction pathway is COOCH_(3)-COOCH_(3)coupling pathway over these four catalysts,while the rate-controlling step is COOCH_(3)+CO+OCH_(3)→2COOCH_(3)on Pd stripe doping Co(111)surface,which is different from the case(2COOCH_(3)→DMO)on pure Pd(111),Pd monolayer supporting on Co(111)and Pd single atom doping Co(111)surface.This study can contribute a certain reference value for developing Pd-based catalysts with high efficiency and low Pd usage for CO oxidative coupling to DMO.

ALKALINE PRETREATMENT AND AIR MIXING FOR IMPROVEMENT OF METHANE PRODUCTION FROM ANAEROBIC CO-DIGESTION OF POULTRY LITTER WITH WHEAT STRAW

Alkaline pretreatment(AL)and air mixing(air)both have the potential to improve anaerobic co-digestion(Co-AD)of poultry litter with wheat straw for methane production.In this study,the effects of the combination of AL(pH 12 for 12 h)and air mixing(12 mL·d^(−1))on the Co-AD process were investigated.The substrate hydrolysis was enhanced by AL,with soluble chemical oxygen demand increased by 4.59 times and volatile fatty acids increased by 5.04 times.The cumulative methane yield in the group of Co-AD by AL integrated with air(Co-(AL+air)),being 287 mL·(g VS_(added))^(−1),was improved by 46.7%compared to the control.The cone model was found the best in simulating the methane yield kinetics with R^(2)≥0.9979 and root mean square prediction error(rMSPE)≤3.50.Co-(AL+air)had a larger hydrolysis constant k(0.14 d^(−1))and a shorter lag phaseλ(0.99 d)than the control(k=0.12 d^(−1),λ=2.06 d).The digestate improved the removal of total solids and total volatile solids by 2.0 and 2.3 times,respectively.AL facilitated substrate degradation,while air can enrich the microbial activity,together enhancing the methane generation.The results show that AL+air can be applied as an effective method to improve methane production from the Co-AD process.