The reaction order plays a crucial role in evaluating the response rate of acid-rock.However,the conventional two-scale model typically assumes that the reaction order is constant as one,which can lead to significant ...The reaction order plays a crucial role in evaluating the response rate of acid-rock.However,the conventional two-scale model typically assumes that the reaction order is constant as one,which can lead to significant deviations from reality.To address this issue,this study proposes a novel multi-order dynamic model for acid-rock reaction by combining rotating disk experimental data with theoretical derivation.Through numerical simulations,this model allows for the investigation of the impact of acidification conditions on different orders of reaction,thereby providing valuable insights for on-site construction.The analysis reveals that higher response orders require higher optimal acid liquid flow rates,and lower optimal H+diffusion coefficients,and demonstrate no significant correlation with acid concentration.Consequently,it is recommended to increase the displacement and use high-viscosity acid for reservoirs with high calcite content,while reducing the displacement and using low-viscosity acid for reservoirs with high dolomite content.展开更多
Carbonate minerals and water （or geofluids） reactions are important for modeling of geochemical processes and have received considerable attention over the past decades. The calcite dissolution rates from 50℃ to 25...Carbonate minerals and water （or geofluids） reactions are important for modeling of geochemical processes and have received considerable attention over the past decades. The calcite dissolution rates from 50℃ to 250℃ at 10 MPa in deionized water with a flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. The dissolution began near the equilibrium with c/ceq 〉 0.3 and finally reached the equilibrium at 100℃-250℃, so the corresponding solubility was also determined as 1.87, 2.02, 2.02 and 1.88×10^-4.mol/L at 100℃, 150℃, 200℃ and 250℃ respectively, which was first increasing and then switching to decreasing with temperature and the maximum value might occur between 150℃ and 200℃. The experimental dissolution rate not only increased with temperature, but also had a rapid increase between 150℃ and 200℃ at a constant flow rate of 4 mL/min. The measured dissolution rates can be described using rate equations of R = k（1-c/ceq）n or R = kc-n. In these equations the reaction order n changed with temperature, which indicates that n was a variable rather than a constant, and the activation energy was 13.4 kJ/mol calculated with R = k（1-c/ceq）n or 18.0 kJ/mol with R = kc^-n, which is a little lower than the surface controlled values. The varied reaction order and lower activation energy indicates that calcite dissolution in this study is a complex interplay of diffusion controlled and surface controlled processes.展开更多
The kinetics of the catalytic reforming reaction of methane with carbondioxide to produce synthesis gas on a Ni/α-Al_2O_3 and a HSD-2 type commercial catalyst has beenstudied. The results indicate that the reaction o...The kinetics of the catalytic reforming reaction of methane with carbondioxide to produce synthesis gas on a Ni/α-Al_2O_3 and a HSD-2 type commercial catalyst has beenstudied. The results indicate that the reaction orders are one and zero for methane and carbondioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and thetemperature was at 1123-1173 K. However, when the carbon dioxide partial pressure was changed to30.0-45.0 kPa under the same temperature range of 1123-1173 K, the reaction orders of methane andcarbon dioxide are one. Furthermore, average rate constants at different temperatures weredetermined.展开更多
With a new approach,the general current expressions of two typical second order catalytic reactions at microelectrodes are obtained.This allows the study of fast chemical reactions and systems where the reactants are ...With a new approach,the general current expressions of two typical second order catalytic reactions at microelectrodes are obtained.This allows the study of fast chemical reactions and systems where the reactants are present in similar concentrations.展开更多
Metal-free, heteroatom functionalized carbon-based catalysts have made remarkable progress in recent years in a wide range of applications related to energy storage and energy generation. In this study, high surface a...Metal-free, heteroatom functionalized carbon-based catalysts have made remarkable progress in recent years in a wide range of applications related to energy storage and energy generation. In this study, high surface area mesoporous ordered sulphur doped carbon materials are obtained via one-pot hydrothermal synthesis of carbon/SBA-15 composite after removal of in-situ synthesized hard template SiO2. 2-thiophenecarboxy acid as sulphur source gives rise to sulphur doping level of 5.5 wt%. Comparing with pristine carbon, the sulphur doped mesoporous ordered carbon demonstrates improved electro-catalytic activity in the oxygen reduction reaction in alkaline solution. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps...The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps.And its validity has been verified by the ex- perimental results.展开更多
In the current work,inclined magnetic field,thermal radiation,and the Cattaneo-Christov heat flux are taken into account as we analyze the impact of chemical reaction on magneto-hydrodynamic Casson nanofluid flow on a...In the current work,inclined magnetic field,thermal radiation,and the Cattaneo-Christov heat flux are taken into account as we analyze the impact of chemical reaction on magneto-hydrodynamic Casson nanofluid flow on a stretching sheet.Modified Buongiorno’s nanofluid model has been used to model the flow governing equations.The stretching surface is embedded in a porousmedium.By using similarity transformations,the nonlinear partial differential equations are transformed into a set of dimensionless ordinary differential equations.The numerical solution of transformed dimensionless equations is achieved by applying the shooting procedure together with Rung-Kutta 4th-order method employing MATLAB.The impact of significant parameters on the velocity profile f(ζ),temperature distributionθ(ζ),concentration profileϕ(ζ),skin friction coefficient(Cf),Nusselt number(Nux)and Sherwood number(Shx)are analyzed and displayed in graphical and tabular formats.With an increase in Casson fluid 0.5<β<2,the motion of the Casson fluid decelerates whereas the temperature profile increases.As the thermal relation factor expands 0.1<γ1<0.4,the temperature reduces,and consequently thermal boundary layer shrinks.Additionally,by raising the level of thermal radiation 1<Rd<7,the temperature profile significantly improves,and an abrupt expansion has also been observed in the associated thermal boundary with raise thermal radiation strength.It was observed that higher permeability 0<K<4 hinders the acceleration of Casson fluid.Higher Brownian motion levels 0.2<Nb<0.6 correspond to lower levels of the Casson fluid concentration profile.Moreover,it is observed that chemical reaction 0.2<γ2<0.5 has an inverse relation with the concentration level of Casson fluid.The current model’s significant uses include heat energy enhancement,petroleum recovery,energy devices,food manufacturing processes,and cooling device adjustment,among others.Furthermore,present outcomes have been found in great agreementwith already publishedwork.展开更多
In this work, nitrogen-doped cobalt nanoparticlesinitrogen-doped plate-like ordered mesoporous carbons (N/Co/OMCs) were used as noble-metal free electrocatalysts with high catalytic efficiency. Compared with OMCs with...In this work, nitrogen-doped cobalt nanoparticlesinitrogen-doped plate-like ordered mesoporous carbons (N/Co/OMCs) were used as noble-metal free electrocatalysts with high catalytic efficiency. Compared with OMCs with long channel length, due to more entrances for catalytic target accessibility and a short pathway for rapid diffusion, the utilization efficiency of cobalt nanoparticles inside the plate-like OMCs with short pore length is well improved, which can take full advantage of porous structure in electrocatalysis and increase the utilization of catalysts. The active sites in N/Co/OMCs for oxygen reduction reaction (ORR) are highly exposed to oxygen molecule, which results in a high activity for ORR. By combination of the catalytic properties of nitrogen dopant, incorporation of Co nanoparticles, and structural properties of OMCs, the N/Co/plate-like OMCs are highly active noble-metal free catalysts for ORR in alkaline solution. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
The equations of the second and third order derivative curves of time with respect to potential for a reversible process in adsorption chronopotentiometry are derived and experimentally verified.
A combined approximate scheme is defined for convection-diffusion-reaction equations. This scheme is constructed by two methods. Standard mixed finite element method is used for diffusion term. A second order characte...A combined approximate scheme is defined for convection-diffusion-reaction equations. This scheme is constructed by two methods. Standard mixed finite element method is used for diffusion term. A second order characteristic finite element method is presented to handle the material derivative term, that is, the time derivative term plus the convection term. The stability is proved and the L2-norm error estimates are derived for both the scalar unknown variable and its flux. The scheme is of second order accuracy in time increment, symmetric, and unconditionally stable.展开更多
A mathematical model comprising of nonlinear reaction, diffusion, and convection mechanisms seen in natural and anthropogenic processes is numerically investigated here. It is proposed that a higher order numerical sc...A mathematical model comprising of nonlinear reaction, diffusion, and convection mechanisms seen in natural and anthropogenic processes is numerically investigated here. It is proposed that a higher order numerical scheme of finite difference method be used in conjunction with an iterative approach in order to solve the nonlinear one dimensional convection-diffusion-reaction equation. To account for the wide variety of physical characteristics and boundary conditions, an iterative approach is presented that yields a reliable and precise solution every time. We examined the accuracy and operational efficiency of two distinct finite difference approaches. The efficiency of the system is determined by comparing the estimated results to the appropriate analytical solution by adhering to established norms. Coherence and convergence were analyzed for each approach. The simulation results demonstrate the efficacy and accuracy of these methods in solving nonlinear convection- diffusion-reaction equations. Convection-diffusion-reaction equation modeling is critical for employing the offered results in heat and mass transport processes.展开更多
The prepolymerization and curing reaction kinetics of polyurethane/montmorillonite have been studied with end group analysis and FTIR respectively. It was found that the prepolymerization and curing reaction followed ...The prepolymerization and curing reaction kinetics of polyurethane/montmorillonite have been studied with end group analysis and FTIR respectively. It was found that the prepolymerization and curing reaction followed the 2nd-order kinetics. But the activation energy of prepolymerization increased from 42.7 kJ/mol to 56.5 kJ/rnol after the montmorillonite was added in the reaction system, and activation energy of curing reaction decreased from 64.4 kJ/mol to 17.5 kJ/mol. 2007 Bing Liao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
基金financially supported by the National Natural Science Foundation of China(Project No.51874336)the National Key Technologies Research and Development Program of China during the 13th Five-Year Plan Period(Project No.2017ZX005030005)。
文摘The reaction order plays a crucial role in evaluating the response rate of acid-rock.However,the conventional two-scale model typically assumes that the reaction order is constant as one,which can lead to significant deviations from reality.To address this issue,this study proposes a novel multi-order dynamic model for acid-rock reaction by combining rotating disk experimental data with theoretical derivation.Through numerical simulations,this model allows for the investigation of the impact of acidification conditions on different orders of reaction,thereby providing valuable insights for on-site construction.The analysis reveals that higher response orders require higher optimal acid liquid flow rates,and lower optimal H+diffusion coefficients,and demonstrate no significant correlation with acid concentration.Consequently,it is recommended to increase the displacement and use high-viscosity acid for reservoirs with high calcite content,while reducing the displacement and using low-viscosity acid for reservoirs with high dolomite content.
文摘Carbonate minerals and water （or geofluids） reactions are important for modeling of geochemical processes and have received considerable attention over the past decades. The calcite dissolution rates from 50℃ to 250℃ at 10 MPa in deionized water with a flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. The dissolution began near the equilibrium with c/ceq 〉 0.3 and finally reached the equilibrium at 100℃-250℃, so the corresponding solubility was also determined as 1.87, 2.02, 2.02 and 1.88×10^-4.mol/L at 100℃, 150℃, 200℃ and 250℃ respectively, which was first increasing and then switching to decreasing with temperature and the maximum value might occur between 150℃ and 200℃. The experimental dissolution rate not only increased with temperature, but also had a rapid increase between 150℃ and 200℃ at a constant flow rate of 4 mL/min. The measured dissolution rates can be described using rate equations of R = k（1-c/ceq）n or R = kc-n. In these equations the reaction order n changed with temperature, which indicates that n was a variable rather than a constant, and the activation energy was 13.4 kJ/mol calculated with R = k（1-c/ceq）n or 18.0 kJ/mol with R = kc^-n, which is a little lower than the surface controlled values. The varied reaction order and lower activation energy indicates that calcite dissolution in this study is a complex interplay of diffusion controlled and surface controlled processes.
文摘The kinetics of the catalytic reforming reaction of methane with carbondioxide to produce synthesis gas on a Ni/α-Al_2O_3 and a HSD-2 type commercial catalyst has beenstudied. The results indicate that the reaction orders are one and zero for methane and carbondioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and thetemperature was at 1123-1173 K. However, when the carbon dioxide partial pressure was changed to30.0-45.0 kPa under the same temperature range of 1123-1173 K, the reaction orders of methane andcarbon dioxide are one. Furthermore, average rate constants at different temperatures weredetermined.
文摘With a new approach,the general current expressions of two typical second order catalytic reactions at microelectrodes are obtained.This allows the study of fast chemical reactions and systems where the reactants are present in similar concentrations.
基金supported by the University of Electronic Science and Technology of China(Y02002010301080)the National Science Foundation of China(51502032)the financial support from Natural Science Foundation of Zhejiang Province(No.LQ14E020003)
文摘Metal-free, heteroatom functionalized carbon-based catalysts have made remarkable progress in recent years in a wide range of applications related to energy storage and energy generation. In this study, high surface area mesoporous ordered sulphur doped carbon materials are obtained via one-pot hydrothermal synthesis of carbon/SBA-15 composite after removal of in-situ synthesized hard template SiO2. 2-thiophenecarboxy acid as sulphur source gives rise to sulphur doping level of 5.5 wt%. Comparing with pristine carbon, the sulphur doped mesoporous ordered carbon demonstrates improved electro-catalytic activity in the oxygen reduction reaction in alkaline solution. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
文摘The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps.And its validity has been verified by the ex- perimental results.
文摘In the current work,inclined magnetic field,thermal radiation,and the Cattaneo-Christov heat flux are taken into account as we analyze the impact of chemical reaction on magneto-hydrodynamic Casson nanofluid flow on a stretching sheet.Modified Buongiorno’s nanofluid model has been used to model the flow governing equations.The stretching surface is embedded in a porousmedium.By using similarity transformations,the nonlinear partial differential equations are transformed into a set of dimensionless ordinary differential equations.The numerical solution of transformed dimensionless equations is achieved by applying the shooting procedure together with Rung-Kutta 4th-order method employing MATLAB.The impact of significant parameters on the velocity profile f(ζ),temperature distributionθ(ζ),concentration profileϕ(ζ),skin friction coefficient(Cf),Nusselt number(Nux)and Sherwood number(Shx)are analyzed and displayed in graphical and tabular formats.With an increase in Casson fluid 0.5<β<2,the motion of the Casson fluid decelerates whereas the temperature profile increases.As the thermal relation factor expands 0.1<γ1<0.4,the temperature reduces,and consequently thermal boundary layer shrinks.Additionally,by raising the level of thermal radiation 1<Rd<7,the temperature profile significantly improves,and an abrupt expansion has also been observed in the associated thermal boundary with raise thermal radiation strength.It was observed that higher permeability 0<K<4 hinders the acceleration of Casson fluid.Higher Brownian motion levels 0.2<Nb<0.6 correspond to lower levels of the Casson fluid concentration profile.Moreover,it is observed that chemical reaction 0.2<γ2<0.5 has an inverse relation with the concentration level of Casson fluid.The current model’s significant uses include heat energy enhancement,petroleum recovery,energy devices,food manufacturing processes,and cooling device adjustment,among others.Furthermore,present outcomes have been found in great agreementwith already publishedwork.
基金financial support from the National Natural Science Foundation of China(21405011)the Science and Technology Development Planning of Jilin Province(20150520014JH)
文摘In this work, nitrogen-doped cobalt nanoparticlesinitrogen-doped plate-like ordered mesoporous carbons (N/Co/OMCs) were used as noble-metal free electrocatalysts with high catalytic efficiency. Compared with OMCs with long channel length, due to more entrances for catalytic target accessibility and a short pathway for rapid diffusion, the utilization efficiency of cobalt nanoparticles inside the plate-like OMCs with short pore length is well improved, which can take full advantage of porous structure in electrocatalysis and increase the utilization of catalysts. The active sites in N/Co/OMCs for oxygen reduction reaction (ORR) are highly exposed to oxygen molecule, which results in a high activity for ORR. By combination of the catalytic properties of nitrogen dopant, incorporation of Co nanoparticles, and structural properties of OMCs, the N/Co/plate-like OMCs are highly active noble-metal free catalysts for ORR in alkaline solution. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
文摘The equations of the second and third order derivative curves of time with respect to potential for a reversible process in adsorption chronopotentiometry are derived and experimentally verified.
文摘A combined approximate scheme is defined for convection-diffusion-reaction equations. This scheme is constructed by two methods. Standard mixed finite element method is used for diffusion term. A second order characteristic finite element method is presented to handle the material derivative term, that is, the time derivative term plus the convection term. The stability is proved and the L2-norm error estimates are derived for both the scalar unknown variable and its flux. The scheme is of second order accuracy in time increment, symmetric, and unconditionally stable.
文摘A mathematical model comprising of nonlinear reaction, diffusion, and convection mechanisms seen in natural and anthropogenic processes is numerically investigated here. It is proposed that a higher order numerical scheme of finite difference method be used in conjunction with an iterative approach in order to solve the nonlinear one dimensional convection-diffusion-reaction equation. To account for the wide variety of physical characteristics and boundary conditions, an iterative approach is presented that yields a reliable and precise solution every time. We examined the accuracy and operational efficiency of two distinct finite difference approaches. The efficiency of the system is determined by comparing the estimated results to the appropriate analytical solution by adhering to established norms. Coherence and convergence were analyzed for each approach. The simulation results demonstrate the efficacy and accuracy of these methods in solving nonlinear convection- diffusion-reaction equations. Convection-diffusion-reaction equation modeling is critical for employing the offered results in heat and mass transport processes.
文摘The prepolymerization and curing reaction kinetics of polyurethane/montmorillonite have been studied with end group analysis and FTIR respectively. It was found that the prepolymerization and curing reaction followed the 2nd-order kinetics. But the activation energy of prepolymerization increased from 42.7 kJ/mol to 56.5 kJ/rnol after the montmorillonite was added in the reaction system, and activation energy of curing reaction decreased from 64.4 kJ/mol to 17.5 kJ/mol. 2007 Bing Liao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
