Methylcyclopentenyl cations(MCP+)have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation...Methylcyclopentenyl cations(MCP+)have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation(triMCP+)and its deprotonated counterpart(trimethylcyclopentadiene,tri MCP)were directly captured on H-RUB-50 catalyst with small cavity by the aid of in situ 13C MAS NMR spectroscopy,and their higher catalytic reactivity were clarified by 12C/13C-CH3OH isotopic switch experiment.In this contribution,an alternative route-cyclopentadienes-based cycle was applied on methanol conversion catalyzed on the H-RUB-50,in which ethene was produced with the participation of tri MCP+as critical intermediate.Then the cyclopentadienes-based cycle was predicted to be energetically favorable for ethene formation by density functional theory(DFT)calculations.The energetic comparison of paring mechanism in the aromatics-based cycle and cyclopentadienes-based cycle with the involvements of trimethylcyclopentadienyl(tri MCPdi+)and tri MCP+as the corresponding active intermediates suggests that cyclopentadienes-based cycle is a feasible route for ethene formation.Furthermore,this work highlights the importance of the steric constraint and the host-guest interaction induced by the zeolite with cavity structure in the formation of intermediates and reaction pathway.展开更多
A series of porous microspheres of linear and ethylene diacrylate (M') cross-linked copolymers of 2-vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dic...A series of porous microspheres of linear and ethylene diacrylate (M') cross-linked copolymers of 2-vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dicarbonylrhodium chelate complex (MVRh and MVM 'Rh). They are thermally stable yet very reactive in the carbonylation of methanol to acetic acid, and of methanol-acetic acid mixture to acetic acid and acetic anhydride with a selectivity of 100% under relatively mild and anhydrous conditions.展开更多
以强酸型阳离子交换树脂为催化剂,甲醇、稀甲醛为原料在间歇反应釜中合成甲缩醛(二甲氧基甲烷)。实验中,各组分的测定采用校正面积归一化法与亚硫酸钠分析法相结合的方式。通过实验,考察了催化剂用量与不同温度对甲醛反应速率的影响,测...以强酸型阳离子交换树脂为催化剂,甲醇、稀甲醛为原料在间歇反应釜中合成甲缩醛(二甲氧基甲烷)。实验中,各组分的测定采用校正面积归一化法与亚硫酸钠分析法相结合的方式。通过实验,考察了催化剂用量与不同温度对甲醛反应速率的影响,测定了反应平衡常数。文章采用拟均相模型对实验数据进行拟合,考察了313,318,323,328 K 4个温度下的正逆反应速率。实验结果表明:催化剂A的最佳用量为总溶液质量分数的3%;采用拟均相模型对实验线性拟合,线性关系显著,验证了假设的反应机理,并回归得到了在313—328 K下的指前因子k0、活化能Ea及宏观动力学方程,反应表现级数为二级。通过对实验与计算值的比较验证,此宏观动力学方程合理,可用于模拟计算。展开更多
Migration regularities of impurities C,O,Fe,Co and Ni and the effect of crystal transition on C,O and Fe in purification of metal La by solid-state electrotransport(SSE)were studied.The impurity migration direction,re...Migration regularities of impurities C,O,Fe,Co and Ni and the effect of crystal transition on C,O and Fe in purification of metal La by solid-state electrotransport(SSE)were studied.The impurity migration direction,removal extent and difficulty were intuitively judged by impurity residual rate distribution curve.It is indicated that major impurities Fe,Co,Ni,C and O in metal La are found to significantly migrate to anode and migration effects are much better with the increase in temperature and prolongation of time in purification of La by SSE.Impurities Fe,Co and Ni in La may be fast diffusion elements,which are very extreme to be removed,and removal difficulty is in the order of Fe<Co<Ni<O<C.When La was migrated for 100 h at 800℃by SSE,the residual rates of impurity Fe,Co,Ni,O and C are 0.25%,10.10%,40.04%,64.00%and 70.04%,respectively.The crystal transition of La,transformed from fcc crystal to bcc crystal,has significant effect on migration of interstitial impurities,and removal effect of interstitial impurities C and O can be significantly improved when purification was performed above crystal transition temperature of 865℃of La.However,there is little effect on Fe.When La was migrated at 880℃for 100 h,residual rates of impurities C and O are,respectively,19.90%and 32.67%lower than those at 820℃for 100 h,while that of Fe is lower than0.25%in both situations.Therefore,more pure metal La can be obtained through further increasing temperature,especially above crystal transition temperature of 865℃of La.展开更多
基金the financial support from the National Natural Science Foundation of China(Nos.91745109,21703239 and 21972142)the Key Research Program of Frontier Sciences,CAS,Grant No.QYZDY-SSW-JSC024+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2014165)the International Partnership Program of Chinese Academy of Sciences,Grant No.121421KYSB20180007Liaoning Revitalization Talents Program(XLYC1807227)。
文摘Methylcyclopentenyl cations(MCP+)have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation(triMCP+)and its deprotonated counterpart(trimethylcyclopentadiene,tri MCP)were directly captured on H-RUB-50 catalyst with small cavity by the aid of in situ 13C MAS NMR spectroscopy,and their higher catalytic reactivity were clarified by 12C/13C-CH3OH isotopic switch experiment.In this contribution,an alternative route-cyclopentadienes-based cycle was applied on methanol conversion catalyzed on the H-RUB-50,in which ethene was produced with the participation of tri MCP+as critical intermediate.Then the cyclopentadienes-based cycle was predicted to be energetically favorable for ethene formation by density functional theory(DFT)calculations.The energetic comparison of paring mechanism in the aromatics-based cycle and cyclopentadienes-based cycle with the involvements of trimethylcyclopentadienyl(tri MCPdi+)and tri MCP+as the corresponding active intermediates suggests that cyclopentadienes-based cycle is a feasible route for ethene formation.Furthermore,this work highlights the importance of the steric constraint and the host-guest interaction induced by the zeolite with cavity structure in the formation of intermediates and reaction pathway.
基金This work was supported by a Grant from the National Natural Science Foundation of China
文摘A series of porous microspheres of linear and ethylene diacrylate (M') cross-linked copolymers of 2-vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dicarbonylrhodium chelate complex (MVRh and MVM 'Rh). They are thermally stable yet very reactive in the carbonylation of methanol to acetic acid, and of methanol-acetic acid mixture to acetic acid and acetic anhydride with a selectivity of 100% under relatively mild and anhydrous conditions.
文摘以强酸型阳离子交换树脂为催化剂,甲醇、稀甲醛为原料在间歇反应釜中合成甲缩醛(二甲氧基甲烷)。实验中,各组分的测定采用校正面积归一化法与亚硫酸钠分析法相结合的方式。通过实验,考察了催化剂用量与不同温度对甲醛反应速率的影响,测定了反应平衡常数。文章采用拟均相模型对实验数据进行拟合,考察了313,318,323,328 K 4个温度下的正逆反应速率。实验结果表明:催化剂A的最佳用量为总溶液质量分数的3%;采用拟均相模型对实验线性拟合,线性关系显著,验证了假设的反应机理,并回归得到了在313—328 K下的指前因子k0、活化能Ea及宏观动力学方程,反应表现级数为二级。通过对实验与计算值的比较验证,此宏观动力学方程合理,可用于模拟计算。
基金financially supported by the National Key Research and Development Program of China(Nos.2017YFB0405900,2017YFB0405901 and 2017YFB0405902)Beijing Xicheng District Talents Project。
文摘Migration regularities of impurities C,O,Fe,Co and Ni and the effect of crystal transition on C,O and Fe in purification of metal La by solid-state electrotransport(SSE)were studied.The impurity migration direction,removal extent and difficulty were intuitively judged by impurity residual rate distribution curve.It is indicated that major impurities Fe,Co,Ni,C and O in metal La are found to significantly migrate to anode and migration effects are much better with the increase in temperature and prolongation of time in purification of La by SSE.Impurities Fe,Co and Ni in La may be fast diffusion elements,which are very extreme to be removed,and removal difficulty is in the order of Fe<Co<Ni<O<C.When La was migrated for 100 h at 800℃by SSE,the residual rates of impurity Fe,Co,Ni,O and C are 0.25%,10.10%,40.04%,64.00%and 70.04%,respectively.The crystal transition of La,transformed from fcc crystal to bcc crystal,has significant effect on migration of interstitial impurities,and removal effect of interstitial impurities C and O can be significantly improved when purification was performed above crystal transition temperature of 865℃of La.However,there is little effect on Fe.When La was migrated at 880℃for 100 h,residual rates of impurities C and O are,respectively,19.90%and 32.67%lower than those at 820℃for 100 h,while that of Fe is lower than0.25%in both situations.Therefore,more pure metal La can be obtained through further increasing temperature,especially above crystal transition temperature of 865℃of La.
