Formation of styrene carbonate (SC) by the cycloaddition of CO2 to styrene oxide (SO) catalysed by pyrrolidinopyridinium iodide (PPI) in combination with zinc halides (ZnCl2, ZnBr2 and ZnI2) was investigated. Complete...Formation of styrene carbonate (SC) by the cycloaddition of CO2 to styrene oxide (SO) catalysed by pyrrolidinopyridinium iodide (PPI) in combination with zinc halides (ZnCl2, ZnBr2 and ZnI2) was investigated. Complete conversion of the SO to SC was achieved in 3 h with 100% selectivity using 1/0.5 molar (PPI/ZnI2) catalyst ratio under mild reaction conditions i.e., 100℃ and 10 bar CO2 pressure. The synergistic effect of ZnI2 and PPI resulted in more than 7-fold increase in reaction rate than using PPI alone. The cycloaddition reaction demonstrated the first-order dependence with respect to the epoxide, CO2 and catalyst concentrations. Moreover, the kinetic and thermodynamic activation parameters of SC formation were determined using the Arrhenius and Eyring equations. The positive values of △H(42.8 kJ mol^-1) and △G(102.3 kJ mol^-1) revealed endergonic and chemically controlled nature of the reaction, whereas the large negative values of △S(-159.4 J mol^-1 K^-1) indicate a highly ordered activated complex at the transition state. The activation energy for SC formation catalyzed by PPI alone was found to be 73.2 kJ mol^-1 over a temperature range of 100-140℃, which was reduced to 46.1 kJ mol^-1 when using PPI in combination with ZnI2 as a binary catalyst. Based on the kinetic study, a synergistic acid-based reaction mechanism was proposed.展开更多
To meet the rapidly increasing demand for energy and the dramatic depletion of conventional crude oil,it is imperative to utilize sour naphtha.With no coke being produced,oxidative desulfurization(ODS)of naphtha lower...To meet the rapidly increasing demand for energy and the dramatic depletion of conventional crude oil,it is imperative to utilize sour naphtha.With no coke being produced,oxidative desulfurization(ODS)of naphtha lowers its sulfur content and average molecular weight.In this article,we outline a method for heavy naphtha non-extractive ODS using a very stable catalyst.The technique involves the use of a solid catalyst with oxygen gas as the oxidant.This necessitated relatively high mixing intensities;hence a three-phase Oscillatory Baffled Reactor(OBR)was used.The catalyst was based on the zeolite ZSM-5,prepared from natural kaolin by a series of delamination and activation steps and impregnated with Fe.A TiO2 nanolayer was applied,using the sol-gel method,to prevent rapid deactivation.The reactor performance was evaluated to minimize the sulfur content in the naphtha fuel.Due to the protective coating,the sulfur conversion stabilized at 90%.The results of this work establish the use of natural clay-based catalysts in a continuous,three-phase ODS,particularly with regard to proving long-term stability.It also showed that modest ODS can be achieved using an environmentally friendly oxidant,at mild operating conditions,whilst maintaining stability.展开更多
Background:Post-mortem and magnetic resonance imaging(MRI)studies of the central sulcus,as an indicator of motor cortex,have shown that in the general population there is greater representation of the dominant compare...Background:Post-mortem and magnetic resonance imaging(MRI)studies of the central sulcus,as an indicator of motor cortex,have shown that in the general population there is greater representation of the dominant compared to the non-dominant hand.Studies of musicians,who are highly skilled in performing complex finger movements,have suggested this dominance is affected by musical training,but methods and findings have been mixed.Objective:In the present study,an automated image analysis pipeline using a 3D mesh approach was applied to measure central sulcus(CS)asymmetry on MR images obtained for a cohort of right-handed pianists and matched controls.Methods:The depth,length,and surface area(SA)of the CS and thickness of the cortical mantle adjacent to the CS were measured in each cerebral hemisphere by applying the BrainVISA Morphologist 2012 software pipeline to 3D T1-weighted MR images of the brain obtained for 15 right-handed pianists and 14 controls,matched with respect to age,sex,and handedness.Asymmetry indices(AIs)were calculated for each parameter and multivariate analysis of covariance(MANCOVA),and post hoc tests were performed to compare differences between the pianist and control groups.Results:A one-way MANCOVA across the four AIs,controlling for age and sex,revealed a significant main effect of group(P=0.04),and post hoc analysis revealed that while SA was significantly greater in the left than the right cerebral hemisphere in controls(P<0.001),there was no significant difference between left and right SA in the pianists(P=0.634).Independent samples t-tests revealed that the SA of right CS was significantly larger in pianists compared to controls(P=0.015),with no between-group differences in left CS.Conclusions:Application of an image analysis pipeline to 3D MR images has provided robust evidence of sig-nificantly increased representation of the non-dominant hand in the brain of pianists compared to age-,sex-,and handedness-matched controls.This finding supports prior research showing structural differences in the central sulcus in musicians and is interpreted to reflect the long-term motor training and high skill level of right-handed pianists in using their left hand.展开更多
基金supported by the Engineering and Physical Science Research Council (EPSRC) funding for Sustainable Polymers (Project reference EP/L017393/1)
文摘Formation of styrene carbonate (SC) by the cycloaddition of CO2 to styrene oxide (SO) catalysed by pyrrolidinopyridinium iodide (PPI) in combination with zinc halides (ZnCl2, ZnBr2 and ZnI2) was investigated. Complete conversion of the SO to SC was achieved in 3 h with 100% selectivity using 1/0.5 molar (PPI/ZnI2) catalyst ratio under mild reaction conditions i.e., 100℃ and 10 bar CO2 pressure. The synergistic effect of ZnI2 and PPI resulted in more than 7-fold increase in reaction rate than using PPI alone. The cycloaddition reaction demonstrated the first-order dependence with respect to the epoxide, CO2 and catalyst concentrations. Moreover, the kinetic and thermodynamic activation parameters of SC formation were determined using the Arrhenius and Eyring equations. The positive values of △H(42.8 kJ mol^-1) and △G(102.3 kJ mol^-1) revealed endergonic and chemically controlled nature of the reaction, whereas the large negative values of △S(-159.4 J mol^-1 K^-1) indicate a highly ordered activated complex at the transition state. The activation energy for SC formation catalyzed by PPI alone was found to be 73.2 kJ mol^-1 over a temperature range of 100-140℃, which was reduced to 46.1 kJ mol^-1 when using PPI in combination with ZnI2 as a binary catalyst. Based on the kinetic study, a synergistic acid-based reaction mechanism was proposed.
基金supported by a grant from Petroleum Research and Development Center,Ministry of Oil,Iraq(No.304/16/1/2022).
文摘To meet the rapidly increasing demand for energy and the dramatic depletion of conventional crude oil,it is imperative to utilize sour naphtha.With no coke being produced,oxidative desulfurization(ODS)of naphtha lowers its sulfur content and average molecular weight.In this article,we outline a method for heavy naphtha non-extractive ODS using a very stable catalyst.The technique involves the use of a solid catalyst with oxygen gas as the oxidant.This necessitated relatively high mixing intensities;hence a three-phase Oscillatory Baffled Reactor(OBR)was used.The catalyst was based on the zeolite ZSM-5,prepared from natural kaolin by a series of delamination and activation steps and impregnated with Fe.A TiO2 nanolayer was applied,using the sol-gel method,to prevent rapid deactivation.The reactor performance was evaluated to minimize the sulfur content in the naphtha fuel.Due to the protective coating,the sulfur conversion stabilized at 90%.The results of this work establish the use of natural clay-based catalysts in a continuous,three-phase ODS,particularly with regard to proving long-term stability.It also showed that modest ODS can be achieved using an environmentally friendly oxidant,at mild operating conditions,whilst maintaining stability.
基金Research assistance from Dr.Emma Moore and funding from the European Commission under the Marie Curie Intra-European Fellowship Programme(EC FP7-2010-PEOPLE-IEF 276529)the Marie Curie Action Networks for Initial Training(EC PITN-GA-2009-238157-EBRAMUS)the Society for Education,Music and Psychology Research(SEMPRE)and by the Reid School of Music,Edinburgh College of Art,University of Edinburgh is gratefully acknowledged.
文摘Background:Post-mortem and magnetic resonance imaging(MRI)studies of the central sulcus,as an indicator of motor cortex,have shown that in the general population there is greater representation of the dominant compared to the non-dominant hand.Studies of musicians,who are highly skilled in performing complex finger movements,have suggested this dominance is affected by musical training,but methods and findings have been mixed.Objective:In the present study,an automated image analysis pipeline using a 3D mesh approach was applied to measure central sulcus(CS)asymmetry on MR images obtained for a cohort of right-handed pianists and matched controls.Methods:The depth,length,and surface area(SA)of the CS and thickness of the cortical mantle adjacent to the CS were measured in each cerebral hemisphere by applying the BrainVISA Morphologist 2012 software pipeline to 3D T1-weighted MR images of the brain obtained for 15 right-handed pianists and 14 controls,matched with respect to age,sex,and handedness.Asymmetry indices(AIs)were calculated for each parameter and multivariate analysis of covariance(MANCOVA),and post hoc tests were performed to compare differences between the pianist and control groups.Results:A one-way MANCOVA across the four AIs,controlling for age and sex,revealed a significant main effect of group(P=0.04),and post hoc analysis revealed that while SA was significantly greater in the left than the right cerebral hemisphere in controls(P<0.001),there was no significant difference between left and right SA in the pianists(P=0.634).Independent samples t-tests revealed that the SA of right CS was significantly larger in pianists compared to controls(P=0.015),with no between-group differences in left CS.Conclusions:Application of an image analysis pipeline to 3D MR images has provided robust evidence of sig-nificantly increased representation of the non-dominant hand in the brain of pianists compared to age-,sex-,and handedness-matched controls.This finding supports prior research showing structural differences in the central sulcus in musicians and is interpreted to reflect the long-term motor training and high skill level of right-handed pianists in using their left hand.
