Fuel Synthesis Process Research Articles

Integrating renewable energy with fuel synthesis: Conceptual framework and future directions

The integration of renewable energy sources with fuel synthesis represents a transformative approach to addressing the twin challenges of energy sustainability and climate change. This review presents a conceptual framework for coupling renewable energy technologies, such as solar, wind, and biomass, with fuel synthesis processes to produce sustainable, zero-carbon fuels. The framework emphasizes the use of renewable electricity for water splitting and carbon dioxide reduction, key steps in synthesizing hydrogen and other synthetic fuels. The conceptual framework highlights the importance of advanced catalysts in enhancing the efficiency and selectivity of these chemical reactions. Innovations in nanostructured catalysts, hybrid materials, and biomimetic approaches are discussed for their potential to significantly improve the performance and durability of catalytic processes. Additionally, the framework underscores the role of advanced characterization techniques and computational modeling in understanding and optimizing catalyst behavior. This integration necessitates addressing technical challenges associated with scaling up production processes from laboratory to industrial levels. These challenges include ensuring the stability and longevity of catalysts under operational conditions, managing the intermittency of renewable energy sources, and developing robust systems for capturing and utilizing carbon dioxide. Furthermore, the economic viability of these integrated systems is critical, requiring cost-effective solutions that leverage earth-abundant materials and optimize the overall energy efficiency. The environmental benefits of integrating renewable energy with fuel synthesis are substantial, offering a pathway to significantly reduce carbon emissions and reliance on fossil fuels. The production of synthetic fuels using renewable energy can lead to a closed carbon cycle, thereby mitigating the impact on climate change and contributing to a sustainable energy future. Future directions in this field involve interdisciplinary research to further enhance catalyst performance, develop new materials, and refine process integration strategies. A roadmap for future development includes prioritizing areas such as improved catalyst design, efficient CO2 capture technologies, and the integration of electrochemical and photochemical systems. This abstract concludes by underscoring the transformative potential of renewable energy-fuel synthesis integration, envisioning a future where sustainable energy practices become the cornerstone of global energy systems. Keywords: Integrating, Renewable Energy, Fuel Synthesis, Future Directions, Framework.

Valorization of purple non-sulfur bacteria biomass from anaerobic treatment of fuel synthesis process wastewater to microbial protein: a means of enhancing food security in arid climates

The global shift from traditional fish farming to aquaculture has created an aquafeed production gap. Hence, the recovery of microbial protein from organic and nutrient-rich agro-industrial wastewaters has been identified as a suitable substitute. However, such waste streams are sparse in arid climes like the Middle East. Thus, this study explores the potential of single-cell protein recovery from a novel waste stream abundant in the region–fuel synthesis process water (FSPW), via anaerobic treatment with purple non-sulfur bacteria (PNSB). The feedstock (COD = 10.3 g/L) amended with essential nutrients was inoculated with a PNSB-dominated mixed culture in replicate 1-L batch fermenters. The wastewater characteristics and microbial biomass assays were performed using standard methods. Around two-thirds of the COD was degraded within 72 h at a rate of 2100 mg L−1d−1, which reduced to about 710 mg L−1d−1 by trial end. Also, total nitrogen levels (90 mg/L) were depleted within 72 h, indicating that nitrogen was a limiting nutrient. In addition, a peak biomass concentration of 1.11±0.037 gvss/L was obtained. Proximate analysis revealed that the biomass consisted of 35% protein, 32% lipid, 16% carbohydrate, 7% ash, 0.5% carotenoids, 0.6% bacteriochlorophylls, and 0.004% coenzyme Q10. Biomass protein’s amino acid profile was comparable to soybean grain and meets dietary requirements for several aquatic livestock. Metal analysis of the biomass and wastewater indicated that nutritionally undesirable metals were undetected. Results show that PNSB not only efficiently degrade FSPW’s organic load but also upcycles the waste to valuable feed constituents, potentially creating a regional circular economy.

Synthesis of Methanol From a Chemical Looping Syngas for the Decarbonization of the Power Sector

Abstract One promising pathway for carbon capture and utilization is represented by the coupling of chemical looping cycles with liquid fuel synthesis processes. Methanol is an interesting fuel for gas turbines engines, due to its potential reduction of NOX and particulate emissions along with the absence of SO2 emissions. In this work, methanol production from the syngas generated by a three-reactors chemical looping process is investigated by mass and energy balances. The cycle is composed by a reducer reactor, where Fe2O3 is reduced to FeO by the injection of a reducing agent; an oxidizer reactor, where FeO reacts with CO2 and H2O to produce a syngas; an air reactor, where Fe3O4 is regenerated to Fe2O3 by ambient air. The produced syngas is then sent to a methanol synthesis plant. Several syngas compositions deriving from different CO2/(H2O+ CO2) molar fractions (1–3) at the oxidizer inlet are taken into account. The resulting methanol flow rates are almost equal in all investigated configurations (about 0.35 t/h). From an energy standpoint, the required electric power is greater for higher hydrogen mole fractions in the syngas. However, the case with 75% H2 content is characterized by the greatest methanol yield (12.6%), carbon efficiency (23%) and a high feed/recirculation ratio (0.80), thus representing the most indicated configuration among the investigated ones. Finally, by burning methanol in a gas turbine, the total CO2 emissions are halved with respect to the case without the system (if the CO2 associated with biogenic carbon in the reducer reactor is considered as net-zero).

Design Optimization of Highly Efficient SOEC Co-Electrolysis Processes

Introduction Research is underway to produce synthetic fuels such as hydrocarbon fuels by reacting hydrogen derived from renewable energy with carbon dioxide and other substances, and their use towards a decarbonized society is being considered.1 In this study, we focus on high-temperature co-electrolysis of CO2 and H2O using a solid oxide electrolysis cell (SOEC), which is one of the promising CO2 conversion technologies. The objective of this study is to evaluate the influence of the electrolysis process and operating conditions on the fuel synthesis process based on heat and mass balance analysis and to propose designs for a new fuel production system. Experimental A commercial chemical process simulation software Aspen Plus was used to simulate a fuel synthesis process using SOEC high-temperature co-electrolysis. In this simulation, H2O and CO2 were considered to be supplied to the SOEC for co-electrolysis, and a fuel synthesis process such as a CH4 production reactor was connected to the outlet of the SOEC to calculate the overall system efficiency. Figure 1 describes an SOEC and a fuel synthesis reactor of the SOEC high-temperature co-electrolysis process created by Aspen Plus. Results and discussion Figure 2 shows one of the simulation results calculated using the process model shown in Figure 1, where the operating temperature of the SOEC is 800 ℃ and the reaction pressure is 1 bar. Figure 2 shows the change in gas composition after the co-electrolysis process in the SOEC by varying H2O flow rate from 1 to 5 mol min-1 relative to CO2 flow rate of 1 mol min-1. As shown in Figure 2, the conversion rate of CO2 to CO increases with increasing H2O flow rate due to the reverse water-gas shift reaction, and the ratio of H2O to CO peaked at H2O/CO2=2, and then gradually decreased. Since the ratio of these gases affects the efficiency of fuel synthesis to CH4 and other downstream gases, we have studied the appropriate fuel synthesis ratio based on the simulation results. In this presentation, we report on the results of the performance evaluation of co-electrolysis and fuel synthesis process based on the obtained simulation results, by conducting electrolysis tests using SOEC cells and evaluating cell performance and downstream gas composition under different operating conditions, based on actual experimental results. Acknowledgements This work was partially supported by JSPS KAKENHI Grant Number JP21K04981. Figure 1

Process Analysis of Chemical Looping Gasification of Biomass for Fischer–Tropsch Crude Production with Net-Negative CO2 Emissions: Part 1

Large-scale biofuel production plants require an efficient gasification process that generates syngas of high quality (with minimal gas contaminants and inert gases) to minimize the extent of the syngas cleaning processes required for liquid biofuel production. This work presents process modeling of the chemical looping gasification (CLG) process for syngas production. The CLG process is integrated with a Fischer–Tropsch synthesis (FTS) process to produce Fischer–Tropsch (FT) crude with net-negative CO2 emissions, enabling process and system-level analyses of this novel biomass-to-liquid process. CLG resembles indirect gasification in an interconnected circulating fluidized bed reactor, where instead of inert bed material, a solid-oxygen carrier, such as mineral ores rich in iron or manganese oxides, is used. The oxygen carrier particles undergo oxidation and reduction in the air reactor and fuel reactor, respectively, thereby providing heat and oxygen for gasification. This work uses data from CLG experiments performed with steel converter slag as the oxygen carrier and investigates its potential when integrated with different downstream gas cleaning trains and the subsequent fuel synthesis process with the primary objective of quantifying and evaluating the performance of the integrated CLG–FT process plant. Syngas with a high energy content of 12 MJ/Nm3 (lower heating value basis) is predicted with a cold gas efficiency of 73%. CO2/CO ratios, higher than indirect biomass gasification, are also predicted in the raw syngas produced; thus, there exists an opportunity to capture biogenic CO2 with a relatively lower energy penalty in the subsequent gas cleaning stages. This work quantifies other key performance indicators, such as heat recovery potential, negative CO2 emission capacity, and FT crude production efficiency of the CLG–FT plant. A 100 MWth CLG plant produces roughly 677–696 barrels per day of FT crude, with net-negative emissions of roughly 180 kilotonnes of CO2 annually.

(Co/Zn) Al2O4 nano catalyst for waste cooking oil catalytic cracking

The current work investigated the preparation of Nano-particles of Co/Zn Al2O4 as a catalyst via co-precipitation method. Several analyses, including BET, XRD, HRTEM, EDX, SEM, and FTIR, were used to characterize it. The analysis revealed that the prepared catalyst had an average surface area of 69.20 m2/g, a cross-sectional area of 16.2 m2/molecule, an average particle size of approximately 28 nm, and a pore size of 0.22 cm3/g. The prepared catalyst was used in a bio fuel synthesis process via thermo-catalytic cracking of waste cooking oil (WCO) in a single step batch reactor. Catalyst loading was tested with different weight percentage of 1.5%, 2%, and 2.5%. The pilot study revealed that the best conditions for optimizing bio jet fuel yield were 400 °C, a catalyst loading of 2%, and a reaction time of 30 min.The optimal cut-off from the distillation process of crude liquid bio fuel product which represents a fraction of bio-jet fuel was in the range from 150 to 240 °C.

Power-to-fuels via solid-oxide electrolyzer: Operating window and techno-economics

Power-to-fuel systems via solid-oxide electrolysis are promising for storing excess renewable electricity by efficient electrolysis of steam (or co-electrolysis of steam and CO2) into hydrogen (or syngas), which can be further converted into synthetic fuels with plant-wise thermal integration. Electrolysis stack performance and durability determine the system design, performance, and long-term operating strategy; thus, solid-oxide electrolyzer based power-to-fuels were investigated from the stack to system levels. At the stack level, the data from a 6000-h stack testing under laboratory isothermal conditions were used to calibrate a quasi-2D model, which enables to predict practical, isothermal stack performance with reasonable accuracy. Feasible stack operating windows meeting various design specifications (e.g., specific syngas composition) were further generated to support the selection of operating points. At the system level, with the chosen similar stack operating points, various power-to-fuel systems, including power-to-hydrogen, power-to-methane, power-to-methanol (dimethyl ether) and power-to-gasoline, were compared techno-economically considering system-level heat integration. Several operating strategies of the stack were compared to address the increase in stack temperature due to degradation. The modeling results show that the system efficiency for producing H2, methane, methanol/dimethyl ether and gasoline decreases sequentially from 94% (power-to-H2) to 64% (power-to-gasoline), based on a higher heating value. Co-electrolysis, which allows better heat integration, can improve the efficiency of the systems with less exothermic fuel-synthesis processes (e.g., methanol/dimethyl ether) but offers limited advantages for power-to-methane and power-to-gasoline systems. In a likely future scenario, where the growing amount of electricity from renewable sources results in increasing periods of a negative electricity price, solid oxide electrolyser based power-to-fuel systems are highly suitable for levelling the price fluctuations in an economic way.

Capturing methanol and dimethoxymethane gases with ionic liquids

In this work, ionic liquid (IL) as green solvent was first proposed for capturing methanol and dimethoxymethane (DMM) gases released in the fuel synthesis process. The hydrophilic IL [EMIM][BF4] was selected from 192 kinds of ILs by the COSMO-RS model. The separation mechanism was revealed at the molecule level in combination with the quantum chemistry calculation. The vapor-liquid equilibrium (VLE) data for the binary mixture of methanol (or DMM) and [EMIM][BF4] were experimentally obtained and compared with the prediction of UNIFAC-Lei model. It was found that the popular UNIFAC-Lei model can predict the VLE of the methanol + [EMIM][BF4] and DMM + [EMIM][BF4] mixtures well. Moreover, the methanol and DMM capture experiments using [EMIM][BF4] as absorbent were carried out, demonstrating the good separation performance. Furthermore, a rigorous equilibrium EQ stage model including the UNIFAC-Lei model parameters was built for simulating and optimizing the methanol and DMM capture processes using [EMIM][BF4] and the conventional benchmark solvent triethylene glycol (TEG) as absorbents at industry level. This work confirmed that capturing methanol and DMM gases with ILs is a typical process intensification method.

Effect of NiMo/Zeolite Catalyst Preparation Method for Bio Jet Fuel Synthesis

Bio jet fuel is an alternative fuel derived from vegetable oil substitutes for conventional aviation fuel. Bio jet fuel can be synthesize through hydrodeoxygenation and catalytic cracking process pathways that influence by the catalyst. The success rates of bio jet synthesis with catalysts influence by the characteristic and activity of the catalysts. One factor that influence the catalyst characteristic and activity is the preparation method. This study focuses on the preparation method of a catalyst by comparing the conventional method of impregnation and the latest microwave polyol method. The impregnation method utilizes stirring up to 24 hours while microwave polyol utilizes a microwave for rapid heating which serves to expand the active core, but the catalyst is not yet known its character and its activity in bio jet fuel synthesis process. In this study, NiMo/Zeolite was synthesized by impregnation method had 232.18 m2/gram surface area and had average crystal size of 49.35 nm. Further, the catalyst was used to synthesized bio jet fuel through a catalytic cracking process, with green diesel from the hydrodeoxygenation process of oleic acid conversion as feed. The result, obtained high enough of conversion by 84.30%, but low yield and selectivity of bio-jet fuel range by 34.77% and 36.43% respectively.

Approaches to accommodate resource variability in the modelling of solar driven gasification processes for liquid fuels synthesis

The vast majority of present commercial gasification and liquid fuels synthesis plants operate continuously and at steady-state because this mode of operation offers lower cost, higher product quality, higher efficiency and larger scale than their batch-process counterparts. They also employ a large number of components, each with their own thermal inertia, which interact together to carefully control the composition and flow-rate at each stage in the process. Hence, any variability in the operation of any one component has a flow-on effect to influence the net cost and performance of the system. For this reason, the reliable modelling of a solar driven gasification process requires accounting both for the full variability of the solar resource not only in the gasifier, but also for all of the downstream components. Since a change in thermal input to the gasifier will influence either the throughput or composition of the product gases, the reliable modelling of the entire process is a challenging task. The development of models to account for the variability of the solar resource for solar gasification processes has, to date, been done most effectively with pseudo-steady models. These assume that all temporal changes are sufficiently slow to allow performance to be modelled as a time-series of steady-state processes, which can then be used with a time-series of historical DNI. Here we review the various approaches that have made previously to account for solar resource variability. We also directly compare the difference between steady-state and pseudo-dynamic approaches with different temporal resolution. This highlights the need to account for resource variability as a first-order effect, since the estimated size and costs of a system modelled in this way differs dramatically from that calculated with an assumed capacity factor. The two main approaches that have been proposed to date to accommodate solar variability are the use of large amounts of syngas storage, which requires further development if it is to become cost effective, or through hybridisation, which offers a cost-effective path to steady-state operation at the expense of a lower solar share. However, further work is required to develop and characterise downstream processing plant for transient operation before the performance of other solar-only liquids fuel synthesis processes can be modelled reliably.

O401 木質系バイオマスからのエネルギー物質生産システムにおけるガス化 : 液体燃料合成プロセスの検討

O401 木質系バイオマスからのエネルギー物質生産システムにおけるガス化 : 液体燃料合成プロセスの検討

Flexible sorption enhanced gasification (SEG) of biomass for the production of synthetic natural gas (SNG) and liquid biofuels: Process assessment of stand-alone and power-to-gas plant schemes for SNG production

A flexible sorption enhanced gasification (SEG) process is assessed in this work, where CaO-based material circulating between gasifier and combustor reactors is adjusted for fulfilling the syngas composition requirements according to the downstream fuel synthesis process. A case study of a synthetic natural gas (SNG) production plant based on this SEG process is presented, which has been analysed under different conditions of gasification temperature or solid circulation. A possible integration of this plant with an electrolysis system for power-to-gas application for balancing the electric grid is also proposed and assessed.SNG production efficiencies as high as 62% (LHV-based) have been found for the production of SNG with final CH4 content of 98%. Excess energy recovered from the process streams can be used for producing electricity in a steam turbine, covering the electric demand in the plant. If credits associated to electricity production are considered, equivalent SNG production efficiencies higher than 70% have been calculated. Efficiencies reported in this work are in the upper limit of the range found in the literature for non-SEG concepts, which require an intermediate conditioning step of WGS and CO2 removal. When coupled with an electrolyser, power-to-gas efficiencies of about 60% have been calculated, in line with stand-alone power to gas methanation systems.

Thermodynamic Analysis and Optimization for the Coal-Based Clean Liquid Fuel Synthesis Process

This work makes thermodynamic analysis and optimization for the coal-based Fischer-Tropsch (FT) process. The thermodynamic analysis results show that under standard conditions the maximum effective carbon conversion is 50% from raw coal (CH0.8O0.1) to hydrocarbon products, and at least 50% carbon is converted into CO2 emission in the coal-based FT process. Subsequently, a new coal-based FT synthesis process is proposed to get minimum water consumption, minimum wastewater emission and maximum energy efficiency. The process contains a pulverized coal gasification unit, water-gas-shift unit and iron-based FT synthesis unit with 50% CO2 selectivity. The H2/CO molar ratio of fresh syngas to the FT synthesis unit is 0.5. The carbon and water footprints analysis results indicate that the effective carbon conversion from raw coal to hydrocarbon products is about 46.0%, and it only consumes 0.102 molar water and generates 0.032 molar wastewater when converts 1 molar coal to hydrocarbon products in the process.

A Thermodynamic Analysis of the Fuel Synthesis System with CO<sub>2</sub> Direct Captured from Atmosphere

Hydrocarbon fuel synthesis with renewable energy and captured CO2is a promising option for CCU and an important approach to sustainable energy. Like photosynthesis of plants, the technology of CO2direct captured from atmosphere with CO2utilization would close the carbon cycle thoroughly. Because of the dilute CO2in the atmosphere, the air capture process faces the challenge of high energy penalty. However, integrated with fuel synthesis process, the air capture process can take advantage of the waste heat produced by syngas production process and the transportation of CO2can also be avoided. In this study, a thermodynamic model of the fuel synthesis system is built through energy and exergy analysis. The thermodynamic contribution of three typical CO2capture technologies, moisture swing air capture, high-temperature swing air capture and traditional amine-based flue gas capture, is studied using the model built. Furthermore, by the sensitivity analysis of the critical parameters of the capture, electrolysis and heat exchange process, the influence of each process on the performance of fuel synthesis system is examined and the approach to improve the efficiency of the total system is proposed.

Study on the Coal-Based Synfuels System Coupled with Nuclear Energy

Coal-based synfuels plants are facing serious pressure on CO2 emissions reduction. Developing the coal-based synfuels system coupled with nuclear energy is an effective approach to reduce CO2 emissions. This work analyzes CO2 emissions features in the coal-based synfuels system, and further investigates three coupling paths between the coal-based synfuels system and nuclear energy. Subsequently, an inherent-safety and low-carbon coal-based synfuels system coupled with nuclear energy is proposed. In the coupled system, valley nuclear power is provided to conventional water electrolyser for hydrogen/oxygen production, and oxygen and hydrogen are supplied to the coal gasification and fuel synthesis processes, respectively. The simulation results show that the coupled system can reduce about 50% raw coal consumption and almost all CO2 emissions compared to the conventional coal-based synfuels system, meanwhile it can improve the peak shaving capacity of nuclear power plants.

Trapping the catalyst working state by amber-inspired hybrid material to reveal the cobalt nanostructure evolution in clean liquid fuel synthesis

It has been a long-term dream for scientists working in the field of catalysis to characterize the catalyst details at any state during the course of reaction under actual working conditions. Here, an amber-inspired hybrid material was designed to trap the catalyst working state generated during the reaction process of cobalt-based Fischer–Tropsch synthesis (FTS), which made the unavailable information for the catalytic clean liquid fuel synthesis processes obtainable via current ex situ characterization techniques. The trapped states were used to study the nanostructure evolution of the air-sensitive active species. In the experiments, the thin films of organic modifier anchored onto the montmorillonite (MMT) supports were designed to prevent the active Co components and phases generated during catalytic reaction from being oxidized when they are exposed to air. Consequently, the changes of the active species such as ε-Co to hcp Co and ε-Co to fcc Co phase transformation, Co nanoparticle growth, reoxidation during reaction, and the structure–property relationship of FTS catalysts were revealed clearly for the first time.

The feasibility and current estimated capital costs of producing jet fuel at sea using carbon dioxide and hydrogen

A comparative cost/benefit and energy balance analysis addresses the critical scientific and technical challenges that impact the economic feasibility of synthesizing up to 100 000 gal per day of jet fuel at sea using carbon dioxide (CO2) and hydrogen (H2) from the sea. Included in this analysis are the capital cost, operation and maintenance, and electrical generation cost for synthesizing jet fuel at sea using either ocean thermal energy conversion or nuclear power processes as the energy source. The results suggest that jet fuel could be produced at sea for $3 to $6/gal. Comparing these costs with current and historical prices of fuel purchased by the Department of Defense provides insight into the economic and operational benefits of a sea-based fuel synthesis process for the Navy.

Experimental investigation of an industrial scale black liquor gasifier. Part 2: Influence of quench operation on product gas composition

Pressurised black liquor gasification combined either with a gas turbine or a catalytic fuel synthesis process is a novel technique for production of green electricity or second generation motor fuels. The composition of the gas produced in the gasifier may be important for the performance of either the gas turbine or the catalytic fuel synthesis process and different operating parameters of the gasifier may affect the composition of the produced gas. The aim of this study was to investigate the influence of some operating parameters on the final gas composition with special attention on the performance of the quench in the gasifier. The results show that system pressure, oxygen/black liquor flow rate ratio and the primary spray flow rate in the quench significantly affect the final gas composition. Furthermore, depending on the cooling rate in the quench, the hot reactor gas composition prior to the quench could either be preserved (high cooling rate) yielding the same final gas composition after the quench as in the hot reactor or shifted (low cooling rate) towards a higher concentration of H2 and CO2.

Gasification of Empty Fruit Bunch and Bagasse Using an Entrained-flow Mode Reactor

Empty fruit bunch (EFB) and bagasse, which are now and in near future quite abundant biomass residues in Southeast Asia, were gasified using steam or (steam + oxygen) as a agent in an entrained-flow type reactor at 900 °C. When using steam alone, EFB was gasified well (carbon conversion rate into gas was defined as gasification over 95%) and the hydrogen-rich gas suitable for liquid fuel synthesis ([H2]/[CO]=about 3-3.6) were obtained. Theoretical value of [H2]/[CO] required for many types of liquid fuel synthesis processes is about 2. However, hydrogen rich gas is desirable, because the processes are stabilized by the excess hydrogen. Bagasse was not so well gasified (gasification rate: about 90%) and the [H2]/[CO] was about 1.5-1.8, which was lower than that of EFB, in spite of being gasified under similar conditions. When adding oxygen to steam, rates of both EFB and bagasse were improved (over 98%). By adding oxygen, the [H2]/[CO] obtained from the EFB decreased from 3.6 to 2.7, which were still high enough for liquid fuel synthesis. The ratio from the bagasse decreased to 1.3, which was much lower than optimum value, 2, for liquid fuel synthesis. Tar yields of all the cases were quite low (2]/[CO]) would be required for liquid fuel synthesis.

Study on direct alcohol/ether fuel synthesis process in bubble column slurry reactor

The recent studies of direct alcohol/ether synthesis process in slurry reactors were reviewed, and the research work in our laboratory was carried out in this paper. a global kinetics model for direct dimethyl ether (DME) synthesis from syngas over a novel Cu-Zn-Al-Zr slurry catalyst was established according to the total of 25 experimental data, and a steady-state one-dimensional mathematical model was further developed in bubble column slurry reactor (BCSR), which was assumed that the bubble phase was plug flow, and the liquid phase was fully mixed flow. The numerical simulations of reactor design of 100000 t/a dimethyl ether pilot plant indicate that higher pressure and lower temperature were favorable to the increase of CO conversion, selectivity of dimethyl ether, product yield and height of slurry bed. The optimal operating conditions for DME synthesis process were obtained: reaction temperature at 240°C, reactor pressure at 5 MPa and reactor diameter of 2.5 m.