Thermochemical splitting of CO_(2) on perovskites for CO production: A review

Energy supply dominated by fossil energy has been and remains the main cause of carbon dioxide emissions,the major greenhouse gas leading to the current grave climate change challenges.Many technical pathways have been proposed to address the challenges.Carbon capture and utilization(CCU) represents one of the approaches and thermochemical CO_(2) splitting driven by thermal energy is a subset of the CCU,which converts the captured CO_(2) into CO and makes it possible to achieve closed-loop carbon recirculation.Redox-active catalysts are among the most critical components of the thermochemical splitting cycles and perovskites are regarded as the most promising catalysts.Here we review the latest advancements in thermochemical cycles based on perovskites,covering thermodynamic principles,material modifications,reaction kinetics,oxygen pressure control,circular strategies,and demonstrations to provide a comprehensive overview of the topical area.Thermochemical cycles based on such materials require the consideration of trade-off between cost and efficiency,which is related to actual material used,operation mode,oxygen removal,and heat recovery.Lots of efforts have been made towards improving reaction rates,conversion efficiency and cycling stability,materials related research has been lacking-a key aspect affecting the performance across all above aspects.Double perovskites and composite perovskites arise recently as a potentially promising addition to material candidates.For such materials,more effective oxygen removal would be needed to enhance the overall efficiency,for which thermochemical or electrochemical oxygen pumps could contribute to efficient oxygen removal as well as serve as means for inert gas regeneration.The integration of thermochemical CO_(2) splitting process with downstream fuel production and other processes could reduce costs and increase efficiency of the technology.This represents one of the directions for the future research.

Advanced Thermochemical Conversion Approaches for Green Hydrogen Production from Crop Residues

The huge volumes of crop residues generated during the production,processing,and consumption of farm products constitute an ecological nuisance when ineffectively managed.The conversion of crop residues to green hydrogen is one of the sustainable management strategies for ubiquitous crop residues.Production of green hydrogen from crop residue sources will contribute to deepening access to clean and affordable energy,mitigating climate change,and ensuring environmental sustainability.However,the deployment of conventional thermochemical technologies for the conversion of crop residues to green hydrogen is costly,requires long residence time,produces low-quality products,and therefore needs to be upgraded.The current review examines the conventional,advanced,and integrated thermochemical conversion technologies for crop residues for green hydrogen production.After a brief overview of the conventional thermochemical techniques,the review delves into the broad narration of advanced thermochemical technologies including catalytic pyrolysis,microwave pyrolysis,co-pyrolysis,hyropyrolysis,and autothermal pyrolysis.The study advocates the deployment of integrated pyrolysis,anaerobic digestion,pyrolysis,and gasification technologies will ensure scalability,decomposition of recalcitrant feedstocks,and generation of high grade green hydrogen.The outlook provides suggestions for future research into cost-saving and sustainable integrated technologies for green hydrogen production towards achieving carbon neutrality and a circular bio-economy.

Mesoscale study on explosion-induced formation and thermochemical response of PTFE/Al granular jet

The dynamic formation,shock-induced inhomogeneous temperature rise and corresponding chemical reaction behaviors of PTFE/Al reactive liner shaped charge jet(RLSCJ)are investigated by the combination of mesoscale simulation,reaction kinetics and chemical energy release test.A two-dimensional granular model is developed with the randomly normal distribution of aluminum particle sizes and the particle delivery program.Then,the granular model is employed to study the shock-induced thermal behavior during the formation and extension processes of RLSCJ,as well as the temperature history curves of aluminum particles.The simulation results visualize the motion and temperature responses of the RLSCJ at the grain level,and further indicate that the aluminum particles are more likely to gather in the last two-thirds of the jet along its axis.Further analysis shows that the shock,collision,friction and deformation behaviors are all responsible for the steep temperature rise of the reactive jet.In addition,a shock-induced chemical reaction extent model of RLSCJ is built based on the combination of the Arrhenius model and the Avrami-Erofeev kinetic model,by which the chemical reaction growth behavior during the formation and extension stages is described quantitatively.The model indicates the reaction extent highly corresponds to the aluminum particle temperature history at the formation and extension stages.At last,a manometry chamber and the corresponding energy release model are used together to study the macroscopic chemical energy release characteristics of RLSCJ,by which the reaction extent model is verified.

Design and synthesis of thermally stable single atom catalysts for thermochemical CO_(2) reduction

The continuous and excessive emission of CO_(2)into the atmosphere presents a pressing challenge for global sustainable development.In response,researchers have been devoting significant efforts to develop methods for converting CO_(2)into valuable chemicals and fuels.These conversions have the potential to establish a closed artificial carbon cycle and provide an alternative resource to depleting fossil fuels.Among the various conversion routes,thermochemical CO_(2)reduction stands out as a promising candidate for industrialization.Within the realm of heterogeneous catalysis,single atom catalysts(SACs)have garnered significant attention.The utilization of SACs offers tremendous potential for enhancing catalytic performance.To achieve optimal activity and selectivity of SACs in CO_(2)thermochemical reduction reactions,a comprehensive understanding of key factors such as single atom metal-support interactions,chemical coordination,and accessibility of active sites is crucial.Despite extensive research in this field,the atomic-scale reaction mechanisms in different chemical environments remain largely unexplored.While SACs have been found successful applications in electrochemical and photochemical CO_(2)reduction reactions,their implementation in thermochemical CO_(2)reduction encounters challenges due to the sintering and/or agglomeration effects that occur at elevated temperatures.In this review,we present a unique approach that combines theoretical understanding with experimental strategies to guide researchers in the design of controlled and thermally stable SACs.By elucidating the underlying principles,we aim to enable the creation of SACs that exhibit stable and efficient catalytic activity for thermochemical CO_(2)reduction reactions.Subsequently,we provide a comprehensive overview of recent literature on noble metal-and transition metal-based SACs for thermochemical CO_(2)reduction.The current review is focused on certain CO_(2)-derived products involving one step reduction only for simplicity and for better understanding the SACs enhancement mechanism.We emphasize various synthesis methods employed and highlight the catalytic activity of these SACs.Finally,we delve into the perspectives and challenges associated with SACs in the context of thermochemical CO_(2)reduction reactions,providing valuable insights for future research endeavor.Through this review,we aim to contribute to the advancement of SACs in the field of thermochemical CO_(2)reduction,shedding light on their potential as effective catalysts and addressing the challenges that need to be overcome for their successful implementation as paradigm shift in catalysis.

Experimental and numerical studies of Ca(OH)_(2)/CaO dehydration process in a fixed-bed reactor for thermochemical energy storage

The Ca(OH)_(2)/CaO thermochemical energy storage(TCES)system based on calcium looping has received extensive attention owing to its high energy storage density,prolonged energy storage time,and environmental friendliness.The heat storage process of the Ca(OH)_(2)/CaO TCES system in a mixed heating reactor was evaluated in this study,by employing a combination of direct and indirect heating modes.The dehydration process was studied experimentally,and a numerical model was established and verified based on the experimental results.The dehydration behavior of 500 g of Ca(OH)_(2) powder was investigated in a fixed-bed reactor with mixed heating.The experimental and simulation results indicated that mixed heating causes combined centripetal and horizontal propulsion.Heat input is the main limiting factor in the heat storage process,because the radial advance of the reaction is hindered by the low thermal conductivity of the solid reactant particles.Heat transmission partitions were added to enhance the performance of the reactor.The performance of the modified reactor was compared with that of a conventional reactor.The radial heat transmission partitions in the modified reactor effectively enhance the energy storage rate and reduce the reaction time by 59.5%compared with the reactor without partitions.

A thermochemical model description of CaO_(2)-SiO2-Al_(2)O_(3) silicate system

A thermochemical model based on the ion and molecule coexistence theory(IMCT)was developed to calculate thermodynamic data in the CaO-SiO_(2)-Al_(2)O_(3) slag system,considering the influential role of oxide activities on the thermodynamic properties of slags.Using this model,iso-activity contours were obtained for oxide components CaO,SiO_(2) and Al2O3 in this system at temperatures of 1,873 K and 1,773 K.When compared with the IMCT model,it is found that the predicted activities of oxide components in the CaO-SiO_(2)-Al_(2)O_(3) system using the model developed in this study better matches experimental data from literature in terms of both trend and numerical value.Therefore,the model developed in this study can serve as a robust modeling tool for metallurgical processes,and the thermodynamic data predicted by this new model can be used to improve the metallurgical technology.

Investigation of Particle Breakdown in the Production of Composite Magnesium Chloride and Zeolite Based Thermochemical Energy Storage Materials

Composite thermochemical energy storage(TCES)represents an exciting field of thermal energy storage which could address the issue of seasonal variance in renewable energy supply.However,there are open questions about their performance and the root cause of some observed phenomena.Some researchers have observed the breakdown of particles in their production phase,and in their use.This study seeks to investigate the underlying cause of this breakdown.SEM and EDX analysis have been conducted on MgCl2 impregnated 13X zeolite composites of differing diameters,as well as LiX zeolite.This was done in order to study the level of impregnation of salt into the zeolite matrix,as well as the effect this impregnation process has on the morphology of the zeolite.Analysis was conducted using ImageJ software to study the effect of the impregnation process on the diameter of the particles.It has been found that a by weight impregnation concentration of magnesium chloride of 11.90%for the LiX zeolite,and 7.59%and 5.26%for the large diameter 13X zeolite and the small diameter 13X zeolite respectively has been achieved.It has been found that the impregnation process significantly affects themorphology of 13X zeolite particles,causing large fissures to form,and eventually resulting in the previously found breakdown of these particles.It has been verified that a primary factor influencing the breakdown of the 13X zeolite particles is the efflorescence and sub-fluorescence phenomena,which leads to a build-up of crystals in the zeolite pores.It has also been found that prolonged impregnation times and the use of high concentration salt solutions in the soaking process can induce significant crystal growth which also leads to the breakdown of these particles.Results demonstrate that LiX zeolite is the optimum host matrix choice in these conditions.These results will allow for the design of more resilient composite TCES particles.

A review of the current state of biofuels production from lignocellulosic biomass using thermochemical conversion routes

The rapid increase in energy demand,the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation sector.Alternate renewable and sustainable sources have become the ultimate solution to overcome the expected depletion of fossil fuels.The conversion of lignocellulosic biomass to liquid(BtL)transportation fuels seems to be a promising path and presents advantages over first generation biofuels and fossil fuels.Therefore,development of BtL systems is critical to increase the potential of this resource in a sustainable and economic way.Conversion of lignocellulosic BtL transportation fuels,such as,gasoline,diesel and jet fuel can be accomplished through various thermochemical processes and processing routes.The major steps for the production of BtL fuels involve feedstock selection,physical pretreatment,production of bio-oil,upgrading of bio-oil to transportation fuels and recovery of value-added products.The present work is aiming to give a comprehensive review of the current process technologies following these major steps and the current scenarios of biomass to liquid facilities for the production of biofuels.

Analysis of Efficiency of the Ship Propulsion System with Thermochemical Recuperation of Waste Heat

One of the basic ways to reduce polluting emissions of ship power plants is application of innovative devices for on-board energy generation by means of secondary energy resources.The combined gas turbine and diesel engine plant with thermochemical recuperation of the heat of secondary energy resources has been considered.It is suggested to conduct the study with the help of mathematical modeling methods.The model takes into account basic physical correlations,material and thermal balances,phase equilibrium,and heat and mass transfer processes.The paper provides the results of mathematical modeling of the processes in a gas turbine and diesel engine power plant with thermochemical recuperation of the gas turbine exhaust gas heat by converting a hydrocarbon fuel.In such a plant,it is possible to reduce the specific fuel consumption of the diesel engine by 20%.The waste heat potential in a gas turbine can provide efficient hydrocarbon fuel conversion at the ratio of powers of the diesel and gas turbine engines being up to 6.When the diesel engine and gas turbine operate simultaneously with the use of the LNG vapor conversion products,the efficiency coefficient of the plant increases by 4%–5%.

Analysis of CO_2 utilization into synthesis gas based on solar thermochemical CH_4-reforming

In this study, the solar thermochemical reactor performance for CO_2 utilization into synthesis gas(H_2+ CO) based on CH_4 reforming process was investigated in the context of carbon capture and utilization(CCU) technologies. The P1 radiation heat transfer model is adopted to establish the heat and mass transfer model coupled with thermochemical reaction kinetics. The reactor thermal behavior with direct heat transfer between gaseous reactant and products evolution and the effects of different structural parameters were evaluated. It was found that the reactor has the potential to utilize by ～60% of CO_2 captured with 40% of CH_4 co-fed into syngas(72.9% of H_2 and 27.1% of CO) at 741.31 k W/mof incident radiation heat flux. However, the solar irradiance heat flux and temperature distribution were found to significantly affect the reactant species conversion efficiency and syngas production. The chemical reaction is mainly driven by the thermal energy and higher species conversion into syngas was observed when the temperature distribution at the inner cavity of the reactor was more uniform. Designed a solar thermochemical reactor able to volumetric store concentrated irradiance could highly improve CCU technologies for producing energy-rich chemicals. Besides, the mixture gas inlet velocity, operating pressure and CO_2/CH_4 feeding ratio were crucial to determining the efficiency of CO_2 utilization to solar fuels. Catalytic CO_2-reforming of CH_4 to chemical energy is a promising strategy for an efficient utilization of CO_2 as a renewable carbon source.

Insights into the thermochemical evolution of maleic anhydride-initiated esterified starch to construct hard carbon microspheres for lithium-ion batteries

Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.

Thermochemical Sulfate Reduction in the Tazhong District,Tarim Basin,Northeast China:Evidence from Formation Water and Natural Gas Geochemistry

Systematic analyses of the formation water and natural gas geochemistry in the Central Uplift of the Tarim Basin （CUTB） show that gas invasion at the late stage is accompanied by an increase of the contents of HeS and CO2 in natural gas, by the forming of the high total dissolved solids formation water, by an increase of the content of HCO3^-, relative to Cl^-, by an increase of the 2nd family ions （Ca^2＋, Mg^2＋, Sr^2＋ and Ba^2＋） and by a decrease of the content of SO4^2-, relative to Cl^-. The above phenomena can be explained only by way of thermochemicai sulfate reduction （TSR）. TSR often occurs in the transition zone of oil and water and is often described in the following reaction formula： ∑CH＋CaSO4＋H-2O→H2S＋CO2＋CaCO3. （1） Dissolved SO4^2- in the formation water is consumed in the above reaction, when HeS and CO2 are generated, resulting in a decrease of SO4^2- in the formation water and an increase of both HeS and CO2 in the natural gas. If formation water exists, the generated CO2 will go on reacting with the carbonate to form bicarbonate, which can be dissolved in the formation water, thus resulting in the enrichment of Ca^2＋ and HCO3^-. The above reaction can be described by the following equation： CO2＋HeO＋CaCO3→Ca^2＋＋2HCO3^-. The stratigraphic temperatures of the Cambrian and lower Ordovician in CUTB exceeded 120℃, which is the minimum for TSR to occur. At the same time, dolomitization, which might be a direct result of TSR, has been found in both the Cambrian and the lower Ordovician. The above evidence indicates that TSR is in an active reaction, providing a novel way to reevaluate the exploration potentials of natural gas in this district.

Thermochemical ablation of spherical cone during re-entry

Presents the use of the similar transform and potential theory for calculation of the bypass flow factor and pressure gradient and the analysis of the influence of bypass flow factor and pressure gradient on heat transfer is analyzed, and the distribution of nose cone ablation obtained by combining the controlling equations of boundary layer, the compatible relation of interface and the heat conduction of interior.

Thermochemical studies on complex of [Sm(o-NBA)_3phen]_2

A ternary complex [Sm(o-NBA)3phen]2 (o-NBA: o-Nitrobenzoate; phen: 1,10-phenanthroline) was synthesized and characterized by elemental analysis, IR, molar conductance, and thermogravimetric analysis. The dissolution enthalpies of SmCl3·6H2O(s), o-HNBA(s) and phen·H2O(s) in mixed solvent (VHCl :VDMF :VDMSO=2:2:1) were determined by calorimetry at 298.15 K. The enthalpy change of the reaction was determined to be rHmΔ θ=252.49±1.60 kJ/mol. Using the relevant data in the literature and a thermochemical recycle...

The First Report of Thermochemical Sulfate Reduction Reaction in the Upper Paleozoic Carbonate Rocks of Southeastern Ordos Basin

Thermochemical sulfate reduction （TSR） is the reaction between anhydrite and petroleum fluids at elevated temperatures to produce H2S and CO2. TSR has been studied in many sedimentary basins such as China＇s Sichuan and Tarim basins because it has a profound impact on the commercial viability of petroleum resources, with HzS typically being undesirable.

Overview of Bio-Oil from Sewage Sludge by Direct Thermochemical Liquefaction Technology

Sewage sludge is an unavoidable secondary pollution produced in the process of sewage treatment. At present traditional methods of treating sludge (e.g. landfill, incineration or land application) have some disadvantages and shortages. Direct thermochemical liquefaction of sludge is a new treatment method, which has the advantage of both treatment and energy recovery. Research progress and application prospect of sludge liquefaction technology are widely reported, typical liquefaction process with bio-oil production and its main influencing factors are introduced. Besides, the devel- opment of this process is illustrated, and resource and energy recovery of this technology are pointed out to be the ten- dency of sludge treatment in the future.

Prediction of concentration of toxic gases produced by detonation of commercial explosives by thermochemical equilibrium calculations

An adverse effect resulting from explosive mine blasts is the production of toxic nitrogen oxides(NO and NO_(2)) and carbon monoxide(CO).The empirical measurements of the concentration of toxic gases showed that it depends not only on the composition of an explosive and properties of its ingredients but also on several other parameters,such as volume of blasting chamber,explosive charge mass and design,confinement characteristics,surrounding atmosphere,etc.That explains why measured concentrations of toxic gases reported in literature significantly differ.In this paper,we discuss the possibility of theoretical prediction of the concentration of toxic gases by thermochemical equilibrium calculation applying two models:ideal detonation model and deflagration model.It can be demonstrated that thermochemical calculations can provide a good estimation of the measured concentrations and reproduce experimentally obtained effects of additives on the production of toxic gases.It was also found that the ideal detonation model applies to heavily confined explosive charges,while the deflagration model is more suitable for low detonation velocity explosives with light confinement.

Computer simulation of thermochemical treatments: modelling diffusion and precipitation in metals

A model for simultaneous diffusion and precipitation in metals has been recently incorporated into a finite element computer code [1][2]. This model allows now for numerical simulations of various thermochemical treatments such as nitriding or carburizing. Subsequent quenching simulations are then made more accurate, by introducing the influence of the carbon content on the thermo-metallurgical and mechanical properties of the materials [3]. After recalling the mathematical equations used to model simultaneous diffusion and precipitation and their implementation into a finite element code, this paper deals with the method used to obtain the local fractions of precipitates as functions of the local content in each chemical element. The law of mass action is employed to calculate the fractions of precipitates obtained at thermodynamic equilibrium. This leads to a nonlinear complementarity problem. The method used to solve this problem is described in detail, and is validated by computing the phase diagram of a micro-alloyed steel. Finally, numerical simulations of combined diffusion and precipitation in steels point out the efficiency of the approach presented, as well as the important role played by precipitation during diffusion in metals.

Flow characteristics simulation of spiral coil reactor used in the thermochemical energy storage system

According to environmental and energy issues,renewable energy has been vigorously promoted.Now solar power is widely used in many areas but it is limited by the weather conditions and cannot work continuously.Heat storage is a considerable solution for this problem and thermochemical energy storage is the most promising way because of its great energy density and stability.However,this technology is not mature enough to be applied to the industry.The reactor is an important component in the thermochemical energy storage system where the charging and discharging process happens.In this paper,a spiral coil is proposed and used as a reactor in the thermochemical energy storage system.The advantages of the spiral coil include simple structure,small volume,and so on.To investigate the flow characteristics,the simulation was carried out based on energy-minimization multi-scale model(EMMS)and Eulerian two-phase model.CaCO_(3) particles were chosen as the reactants.Particle distribution was shown in the results.The gas initial velocity was set to 2 m·s^(-1),3 m·s^(-1),and 4 m·s^(-1).When the particles flowed in the coil,gravity,centrifugal force and drag force influenced their flow.With the Reynold numbers increasing,centrifugal and drag force got larger.Accumulation phenomenon existed in the coil and results showed with the gas velocity increasing,accumulation moved from the bottom to the outer wall of the coil.Besides,the accumulation phenomenon was stabilized whenφ>720°.Also due to the centrifugal force,a secondary flow formed,which means solid particles moved from the inside wall to the outside wall.This secondary flow could promote turbulence and mixing of particles and gas.In addition,when the particle volume fraction is reduced from 0.2 to 0.1,the accumulation at the bottom of the coil decreases,and the unevenness of the velocity distribution becomes larger.

Effects of Porous Graphene on LiOH Based Composite Materials for Low Temperature Thermochemical Heat Storage

Thermochemical heat storage material inorganic hydrate LiOH is selected as a promising candidate material for storing low-temperature heat energy because of its high energy density(1440 kJ/kg)and mild reaction process.However,the low hydration rate of LiOH limits the performance of low temperature thermochemical heat storage system as well as the thermal conductivity.In this study,porous-graphene/LiOH composite thermochemical heat storage materials with strong water sorption property and higher thermal conductivity were synthesized by hydrothermal process.The experimental results show that the hydration rate of the composites was greatly improved.The heat storage density of the composite materials was increased by 47%(from 661 kJ/kg to 974 kJ/kg).By combing the porous graphene,the thermal conductivity of composites with different contents were highly increased by 21.1%to 78.7%,but the increase of heat storage density is opposite to that of thermal conductivity.The development of high-performance materials for thermochemical heat storage should consider the relationship between the heat storage density and thermal conductivity of the material,and the thermal conductivity of the supporter needs to be further improved.