The acidity and surface properties of H 4SiW 12 O 40 Ti(SO 4) 2 La 2O 3 HZSM 5(HTLH) were investigated by means of TEM, TPD and IR spectra. The activity and selectivity of the product as a catalyst f...The acidity and surface properties of H 4SiW 12 O 40 Ti(SO 4) 2 La 2O 3 HZSM 5(HTLH) were investigated by means of TEM, TPD and IR spectra. The activity and selectivity of the product as a catalyst for methanol to dimethylether were studied. The results show that there are Brnsted and Lewis acid sites in HTLH and that the total acidity is concerned with the conversion of methanol and the yield of dimethylether. The catalytic capacity of the acid at 453 K is the best. Keggin unit [SiW 12 O 40 ] 4- deposits on the external HZSM 5 surface only, and it can not permeate through the HZSM 5 pore system.展开更多
Polyoxymethylene dimethyl ethers(OMEs)with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression.Herein,series of SO_(4)^(2-)/ZrO_(2)-TiO_(2...Polyoxymethylene dimethyl ethers(OMEs)with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression.Herein,series of SO_(4)^(2-)/ZrO_(2)-TiO_(2)catalysts were developed for OMEs production from dimethoxymethane(DMM)and1,3,5-trioxane through sequential formaldehyde monomer insertion into C-O bond of DMM.Not Lewis but Bronsted acid sites were identified to be active for the decomposition of 1,3,5-trioxane into formaldehyde unit,however,both of them are effective for the chain propagation of DMM via formaldehyde unit insertion into C-O bond.Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Bronsted and Lewis acid sites due to the same reaction mechanism and very similar chemical structure of OMEs.Also,the catalytic stability investigation suggested the deactivation behavior was derived from the carbon deposition,and the decay factor could be exponentially correlated with the amount of coke accumulation.展开更多
文摘The acidity and surface properties of H 4SiW 12 O 40 Ti(SO 4) 2 La 2O 3 HZSM 5(HTLH) were investigated by means of TEM, TPD and IR spectra. The activity and selectivity of the product as a catalyst for methanol to dimethylether were studied. The results show that there are Brnsted and Lewis acid sites in HTLH and that the total acidity is concerned with the conversion of methanol and the yield of dimethylether. The catalytic capacity of the acid at 453 K is the best. Keggin unit [SiW 12 O 40 ] 4- deposits on the external HZSM 5 surface only, and it can not permeate through the HZSM 5 pore system.
基金the fund from the National Natural Science Foundation of China(22208349)the Innovation Academy for Green Manufacture(Chinese Academy of Sciences,IAGM2020C20)+1 种基金Shandong Provincial Natural Science Youth Fund(ZR2022QB244)Japan Society for the Promotion of Science(P20345)。
文摘Polyoxymethylene dimethyl ethers(OMEs)with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression.Herein,series of SO_(4)^(2-)/ZrO_(2)-TiO_(2)catalysts were developed for OMEs production from dimethoxymethane(DMM)and1,3,5-trioxane through sequential formaldehyde monomer insertion into C-O bond of DMM.Not Lewis but Bronsted acid sites were identified to be active for the decomposition of 1,3,5-trioxane into formaldehyde unit,however,both of them are effective for the chain propagation of DMM via formaldehyde unit insertion into C-O bond.Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Bronsted and Lewis acid sites due to the same reaction mechanism and very similar chemical structure of OMEs.Also,the catalytic stability investigation suggested the deactivation behavior was derived from the carbon deposition,and the decay factor could be exponentially correlated with the amount of coke accumulation.
