Novel carbon-nitride based catalysts for enhanced CH_(4) reforming under visible light: From morphology to heterojunction design principles

The synthesis of high value-added chemical products using CO_(2)and CH_(4)is a promising CO_(2)conversion technology that can reduce greenhouse gas emissions while also alleviating the energy crisis.However,problems such as high energy consumption and strict reaction conditions in reforming process hinder the further development of the technology.In this work,carbon-nitrogen based composites were prepared for the first time according to the design principle from morphology to heterojunction,which is innovatively applied in the process of photocatalytic CH4reforming.Firstly,C_(3)N_(4)materials with different dimensions(D) are prepared and applied to a CO_(2)-CH_(4)photocatalytic system.Additionally,the 2D/2D TiO_(2)/g-C_(3)N_(4)heterostructure is constructed with the ultrasonic impregnation method to further improve charge generation,transfer,and separation efficiency.It is worth noting that the yield of CO reaches173.80 μmol g^(-1),and the catalytic performance is improved by 1546% compared to bulk C_(3)N_(4).Moreover,the physical and chemical properties of 2D/2D TiO_(2)/g-C_(3)N_(4)materials are studied using a variety of cha racterization methods.Furthermore,the work fu nction and adsorption energy of different C3N4/TiO_(2)models for CO_(2)adsorption are calculated by density functional theory(DFT).Then,a possible catalytic mechanism for photocatalytic CO_(2)and CH_(4) conversion is proposed based on DFT calculations and experimental results.This work provides a new technical route for the rapid conversion of CO_(2)and CH_(4) at room temperature,as well as a new research concept for achieving carbon neutrality.

Feasibility analysis and process simulation of CO_(2) dehydration using triethylene glycol for CO_(2) pipeline transportation

The operation of dehydration is very important in the process of gas transportation. This study aims to evaluate the application feasibility of CO_(2) dehydration using triethylene glycol, which is also called TEG for short. Aspen Plus software was used to simulate the dehydration process system of CO_(2) gas transportation using TEG dehydration. Parameter analysis and process improvement were carried out for the simulation of dehydration process. At first, a sensitivity analysis was conducted to analyze and optimize operating conditions of conventional CO_(2)-TEG dehydration process system. Subsequently, a recycle unit was introduced into the conventional CO_(2)-TEG dehydration process system, it can be found that the improved process system with the recycle unit has a higher CO_(2) recovery rate which was about 9.8% than the conventional one. Moreover, the improved process system showed excellent operation stability through the comparison of simulation results of several processes with various water contents in their feed gases. Although the energy consumption is increased by about 2%, the improved process was economically and technically feasible for the long-term availability of CO_(2) pipeline transportation. The simulated results showed that the improved CO_(2)-TEG process system has promising application prospects in CO_(2) dehydration of CO_(2) gas transportation with high stability.

Volumetric and viscometric properties of aqueous 1,2-dimethylethylenediamine solution for carbon capture application

The present work investigates the volumetric and viscometric properties of an aqueous solution of 1,2-dimethylethylenediamine(DEEDA)over an entire concentration range and an absorber operating temperature range of 313.15K-333.15K at atmospheric pressure.The investigated volumetric properties included the density,excess molar volume,partial molar volume,and the investigated viscometric properties included the viscosity,viscosity deviation,free energy for activation of viscous flow,excess free energy for activation of viscous flow,and excess entropy for activation of viscous flow.The results indicated that there are strong intermolecular interactions and suitable molecular packing in the binary DEEDA-water mixture.Hence,the mixture was found to deviate from a real mixture according to the calculated excess properties.The DEEDA solvent's preliminary volumetric and viscometric properties revealed convincing potential as a novel amine for carbon capture.Additionally,the Redlich-Kister-based correlations showed favorable correlative performance for excess molar volume,viscosity deviation,and excess entropy for activation of viscous flow.

Experimental study of the mass transfer behavior of carbon dioxide absorption into ternary phase change solution in a packed tower

Phase change absorbents for CO_(2)are of great interest because they are expected to greatly reduce the heat energy consumption during the regeneration process.Compared with other phase change absorbents,monoethanolamine(MEA)-sulfolane-water is inexpensive and has a fast absorption rate.It is one of the most promising solvents for large-scale industrial applications.Therefore,this study investigates the mass transfer performance of this phase change system in the process of CO_(2)absorption in a packed tower.By comparing the phase change absorbent and the ordinary absorbent,it is concluded that the use of MEA/sulfolane phase change absorbent has significantly improved mass transfer efficiency compared to a single MEA absorbent at the same concentration.In the 4 mol·L^(-1)MEA/5 mol·L^(-1)sulfolane system,the CO_(2)loading of the upper liquid phase after phase separation is almost zero,while the volume of the lower liquid phase sent to the desorption operation is about half of the total volume of the absorbent,which greatly reduces the energy consumption.This study also investigates the influence of operating parameters such as lean CO_(2)loading,gas and liquid flow rates,CO_(2)partial pressure,and temperature on the volumetric mass transfer coefficient(K_(G)α_(V)).The research shows that K_(G)α_(V) increases with increasing liquid flow rate and decreases with the increase of lean CO_(2)loading and CO_(2)partial pressure,while the inert gas flow rate and temperature have little effect on K_(G)α_(V).In addition,based on the principle of phase change absorption,a predictive equation for the K_(G)α_(V) of MEA-sulfolane in the packed tower was established.The K_(G)α_(V) obtained from the experiment is consistent with the model prediction,and the absolute average deviation(AAD)is 7.8%.