Synthesis Gas Generation Research Articles

Techno-Economic Analysis of Hydrogen Generation in Hydrocarbon Reservoirs

Summary To reduce carbon emissions and meet increasing energy demands, efforts are being made to seek clean energy such as hydrogen (or H2). Currently, the dominant method to generate hydrogen is steam methane reforming at a surface plant. It would be ideal to extend this method to subsurface hydrocarbon reservoirs; hydrogen is separated from the other generated gases via a downhole hydrogen-selective membrane separator. By doing so, hydrogen is extracted from the wellhead, and other gases are left in the reservoir. The purpose of this paper is to provide a techno-economic analysis of this idea. The energy of generated hydrogen is compared with the energy of the hydrocarbon feedstock. The hydrogen selectivity (concentration) in the generated synthesis gas (syngas) and the amount of hydrogen generated per unit mass of oil in the literature are reviewed and discussed. The constraints to the hydrogen generation conditions in subsurface reservoirs are discussed. The effectiveness of the downhole membrane is discussed. It is found that the energy from generated hydrogen is much less than the energy input even in a surface reactor where reactants are fully mixed for reactions. In a subsurface reservoir, injected reactants cannot fully mix with the in-situ oil and gas, and reactions may occur only near the flood-front zone of a high temperature. As injected gas (such as steam or oxygen) displaces the oil and gases ahead, the produced hydrocarbons are much higher than hydrogen. Separation of hydrogen from other gases downhole presents challenges in many aspects in reality, such as membrane permeability or separation rate, work life (mechanical and chemical stability), and so on. Therefore, unless a revolutionary technology breakthrough occurs, the generation and production of hydrogen in a subsurface hydrocarbon reservoir may not be feasible.

Prediction of syngas yield from biomass by gasification and related application

This research focuses on the prediction of synthesis gas generation from biomass through gasification and specifically estimates the syngas yield from rice straw from 2018 to 2020. The data of 2020 is visualized in the form of a colored world map A comprehensive literature review is conducted to explore previous studies on syngas yield models and gasification methods and the utilization of machine learning models. A machine learning model is built to calculate the prediction of the syngas total yield generated from biomass gasification. The inputs of the model include temperature, carbon content, hydrogen content, and oxygen content, with the latter three representing different types of biomasses. The output of the model is the total synthesis gas yield per kilogram of biomass. Subsequently, this model is utilized to predict the amount of syngas obtained from rice straw, which has a carbon, hydrogen, and oxygen content of 43.9%, 5.6%, and 32.1% respectively. From the model, an optimal gasification temperature of 667 degrees Celsius and a maximum syngas yield of 4.71 Nm3/kg for rice straw is obtained. Based on available data on rice straw production worldwide from 2018 to 2020, the amount of rice straw utilized for biomass gasification is estimated. The syngas yield in different regions of the world is calculated based on the maximum syngas yield and the mass of available rice straw. Outcomes of the calculation are visualized into a global map displaying the distribution of syngas yields which provides valuable insights into the potential for syngas production from rice straw in different regions.

Lax-Zn3Al2-x-LDO electrocatalyst for effective tunable CO/H2 synthesis gas generation via CO2 reduction

During the electrocatalytic reduction of CO2 (CO2RR), the hydrogen evolution reaction (HER) emerges as an inevitable accompanying reaction. By utilizing the HER, regulating the product distribution of CO2RR can produce CO and H2 synthesis gas, which can convert to different value-added chemicals such as methanol and ethanol. So, La doping ZnAl-LDO catalyst (Lax-Zn3Al2-x-LDO, x = 0, 0.2, 0.4) was prepared by the urea method and was synthesized for CO2RR to CO/H2 synthesis gas. The catalysts are systematically characterized and analyzed by X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and other multinomial characterization techniques to establish the relationship between different doping amounts and catalytic performance. Adding La can change the chemical environment of Zn2+/Al3+ ions and increase CO/H2 ratio range of synthesis gas, but excessive doping of La may result in a decrease in CO/H2 ratio. By precisely controlling the amount of lanthanum doping, meticulous regulation of the CO/H2 ratio in the synthesis gas can be achieved.

Demonstration and scale‐up of high‐temperature electrolysis systems

AbstractHigh‐temperature electrolysis (HTE) is a key to link the electricity sector with other industries and to evolve the electricity transition into a full energy transition. After years of development, HTE is now on the threshold to reach market readiness. The present work shows the latest achievements of Sunfire's development based on the results of the project GrInHy2.0 demonstrating hydrogen production (solid oxide electrolysis cell [SOEC]) in an industrial environment and the project SynLink demonstrating co‐electrolysis (Co‐SOEC) for renewable synthesis gas production. The GrInHy2.0 system is a 720 kWAC electrolyzer operating in the iron‐and‐steel works Salzgitter (Germany). It is now in operation for approx. 14,500 h and achieved a mean degradation rate below 23 mOhm cm2 kh−1 and an electrical efficiency of up to 84%LHV. It also proved that HTE now reached industrial‐relevant availability of over 90%. While the HTE system in Salzgitter consists of eight modules, a single module was tested in co‐electrolysis mode within the project SynLink. It demonstrated synthesis gas generation via Co‐SOEC with a flexible H2/CO ratio between 1 and 4. The work provides insight into how HTE will play a major role in the near future to efficiently produce renewable feedstock for an economy with a drastically reduced carbon footprint.

Prospects for hydrogen production by the method of gasification of MSW at operating TPPs

The work is devoted to the development of a thermal scheme for the conversion of a cogeneration power plant to threegeneration with the production of hydrogen as a new product.The purpose of the work is to assess the possibility and potential of hydrogen production from MSW at the existing thermal power plants of St. Petersburg.To achieve this goal, it is necessary to develop a methodology for selecting the site of an existing thermal power plant in order to integrate a hydrogen production complex by the MSW gasification method, as well as a methodology for estimating the amount of hydrogen that can potentially be obtained from a given amount of MSW. The research methods include simulation of the thermal circuit of a steam power plant in the United Cycle program.The paper proposes an algorithm for selecting the site of an operating thermal power plant for the integration of a complex for the production of hydrogen by the method of MSW gasification. The algorithm can be applied to any subjects of the Russian Federation, and its relevance is confirmed by strategic documents. Potential locations for the new TPP are being considered in the territories of TPP-21 and TPP-22, which have the necessary resources and good infrastructure. As a result of the study, the site of TPP-22 was selected as the most suitable for the placement of new facilities.A new thermal scheme of a threegeneration power plant has been developed, including a hydrogen generation unit by the MSW gasification method. This allows the production of hydrogen in parallel with the production of electricity and heat. The efficiency evaluation criterion is the fuel heat utilization factor (FHUF). Regardless of the hydrogen content in the generated synthesis gas, the integration of the synthesis gas cooler into the thermal circuit of the TPP leads to an increase in the FHUF and an additional energy effect. This scheme increases the efficiency of existing TPP plants, regardless of the morphological composition of municipal solid waste.

Influence of water in catalyst deactivation and lifetime of methane Bi-Reforming reaction over Ni-Co-Ru tri-metallic catalyst system

Recently, the bi-reforming of methane has been an emerging area of interest against conventional synthesis gas generation processes due to the achievable H2/CO ratio of around 2.0 and the possible utilization of feedstock like Biogas substitute to the limited fossil fuel resources. However, commercial implementation still needs to be improved due to the rapid deactivation of catalysts through metal particle sintering and coke formation on active sites. Consequently, developing promising catalysts that can show prolonged stability, high activity, and selectivity during the reaction is worthwhile. A facile synthesis method has been adopted to develop a ceria, magnesia, and zirconia-modified gamma-alumina support. Furthermore, Ni, Co, & Ru metals with varying weight percentages were deposited over the modified support by using a precipitation-deposition approach. The prepared catalysts were well characterized by XRD, XPS, SEM, HRTEM, Physisorption, and Chemisorption studies to elucidate the structure-activity relationship. Ascribed to small particle size, strong metal support interaction, employment of basic promoter MgO and oxygen storage capacitors like ceria and zirconia, and high dispersion of active species, all the catalysts exhibit a higher methane dissociation and carbon dioxide adsorption rate with extended stability. Further, a study has been made to understand how deactivation and catalyst lifetime can be manipulated through the amount of water in the feed composition. It was observed that using 1.8 moles of H2O in the feed can provide a syngas ratio of around 2. Under optimized reaction conditions of temperature 850 °C and weight hourly space velocity 10 Lg−1h−1, the best-selected catalyst exhibits a stable 92% CH4 and 89% CO2 conversion with a studied catalyst lifetime of up to 50 h. After the reaction, the spent catalyst was exposed to Thermogravimetric analysis, Temperature programmed oxidation, and Raman spectroscopy studies, and it was observed that there was a negligible amount of amorphous coke deposited over the catalyst used for 50 h of reaction couldn't have any substantial impact on catalyst activity.

Enhanced syngas production from waste lubricant oil reforming with transition metal catalysts

Waste lubricant oil (WLO) which is a spent oil from vehicles, and machinery is often incinerated or landfilled, leading to environmental pollution and heavy metal-contaminations. At the same time WLO can converted to synthesis gas using steam reforming. In this study, catalytic steam reforming of WLO was performed in a micro fixed bed reactor at atmospheric pressure. Ni and Fe metals were loaded in a ratio of 5% and 10% on dolomite and olivine catalysts through impregnation method. The effects of equivalent ratio (ER) and metal (Ni and Fe) loadings on dolomite and olivine supported catalysts were investigated. Carbon-hydrogen conversions were significantly affected by ER with the optimum data at 0.88, which resulted in low CH4, and high H2 and CO. Nonetheless, the 5%Ni/dolomite exhibited superior overall activity with the highest overall conversion and hydrogen yield. In this case, hydrogen and carbon conversions were 65.71% and 66.38%, respectively, while H2 to CO molar ratio was 1.05 and the lower heating value was 6.76 MJ/m3. Hence, this suggests that the surface-active site of Ni on dolomite has high activity for C–C cleavage and water gas shift reaction. The conversion to H2 and CO was improved through methane and hydrocarbon steam reforming on the catalyst surface. Catalytic reforming of WLO not only enhanced synthesis gas generation which can be readily used as energy, a partial source of H2 or chemical feedstock but also as an appealing, sustainable, and economical waste management alternative.

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ACS NEWS Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2023, 101 (10), p 3March 27, 2023Cite this:C&EN 101, 10, 3Letters to the editorAll about C&ENI have noticed how C&EN has been changing in recent years: for example, fewer science articles and less reader response. The Feb. 13, 2023, issue had no letters to the editor, no chemical reactions, and only one structure (ceramide, page 8). The role of C&EN has never been to “follow the literature,” but it used to regularly highlight outstanding, cutting-edge, novel, or especially interesting chemistry. Not anymore, and I miss it!Howard DeutschAtlantaCongratulations on the forthright explanation of the difficulties with C&EN (Feb. 20/27, 2023, page 2). I have been a reader for almost 70 years and have noticed a troubling trend in recent years that seems to correlate with the changes you have discussed.I’ll state up front that I cannot wait each week to receive C&EN. I find it extremely instructive on worldwide technology, engineering, and business developments in the science I have enjoyed so much.However, in recent years I have been perplexed by the tone and at times context of many issues. This has left me with the feeling that your coverage has been more of a declaration of social trends than technology developments and the people who do them.Please bring us back to balanced coverage of scientific and engineering news important to our industry.Alexander MacLachlanWilmington, DelawareThank you for providing us some information on what happened to the magazine. I have enjoyed C&EN for many years, and it is one of the best news/technical magazines anywhere.I am sad that the fine personnel left but hope you can keep it going.Also, I read the letter from Gordon W. Gribble (Feb. 20/27, 2023, page 3). I wish I could listen to his lectures—what a great method to learn organic chemistry.I hope he writes a textbook.William R. TaskerFort Mill, South CarolinaRe: Turning carbon dioxide into a valuable resourceIn the late 1960s, Monsanto commercialized a breakthrough technology to make acetic acid. The process reacted methanol with carbon monoxide to make high-purity acetic acid in high yield. The first production plant was built at the Monsanto site in Texas City, Texas. The plant generated synthesis gas (carbon monoxide and hydrogen) from methane and steam and made methanol using well-known technology. Then the methanol was reacted with more CO to make acetic acid using the new technology. But the reactions are unbalanced: CH4 + H2O yields CO + 3H2. What one needs is 2CO + 2H2 to make acetic acid. I don’t know how it happened, but some clever person(s) learned that a nearby refinery generated a high-purity stream of carbon dioxide that was just wasted. A short pipeline was built, and that CO2 became the CO (H2 + CO2 = CO + H2O) that balanced the reaction.Louis E. DuPree Jr.Magnolia, TexasIs chemistry magic?It’s great to see American Chemical Society sections doing outreach for National Chemistry Week (C&EN, Feb. 20/27, 2023, page 32). It would be even better if we didn’t do chemistry “magic” shows. Demonstrations are great—keep doing these—but don’t call them magic. We should not be giving kids the idea, even if it’s just “good fun,” that chemistry is magic. It’s not. We are scientists, not wizards or magicians. Let’s do better. Words matter.Bob GotwalsDurham, North Carolina CorrectionsMarch 6, 2023, page 32: The preliminary program for the American Chemical Society Spring 2023 meeting incorrectly implies that the photograph of race cars is from an Indianapolis 500 race. It is from a NASCAR race. Also, the theme of the meeting is “Crossroads of Chemistry,” not “Crossroad of Chemistry.”March 13, 2023, page 15: The feature story about biomanufacturing in the US misstates the university working with Cargill to develop a publicly funded production site. It is Iowa State University, not the University of Iowa.March 13, 2023, page 37: The obituary of Frank H. Clarke has incorrect credits for the obituary remembrance and photo. They are both by Moses K. Kaloustian, not Bernadette Taylor. Also, the degrees earned have the wrong concentration. The BS and MS were in chemistry, not medicinal research.

Phosphorus and nitrogen doped CoNi nanocrystals supported on carbon based materials for electro- reduction of CO2 to syngas with controllable CO/H2

The products of electrocatalytic CO2 reduction reaction (CO2RR) and hydrogen evolution reaction (HER) are the raw materials CO and H2 of synthesis gas respectively. The synthesis gas can generate usable fuel by Fischer Tropsch method to realize the carbon cycle. At present, it is still challenging to control the synthesis gas generation in the low potential and wide potential range. In order to solve this problem, we used a simple template method to embed different proportions of Ni and Co elements in the three-dimensional network structure of carbon carrier, between − 0.55 to − 1.15 V vs RHE, to generate synthetic gas with an adjustable CO/H2 ratio of 0.3–3. When Ni/Co ratio is 2:1(CoNi2 @NCP), the ratio of CO/H2 is kept at 1–3. At the potential of − 1.05 V vs RHE, the Faraday efficiency of CoNi2 @NCP catalyst to produce CO reaches 57 %, and that of H2 reaches 25 %. When the ratio of Ni-Co is 1:1 and 2:1, it can be used to produce methanol, ethanol and other alcohol products. Catalysts with different proportions can generate different synthesis gases at different potentials, which can be better used to generate downstream thermochemical synthesis of methane, ethylene, and alcohols. The sources of CO2RR and HER can be determined as Ni−Nx and Co−Nx sites by electrochemical analysis.

Improving the energy-efficiency of small-scale methanol production through the use of microturboexpander units

The issue of improving the energy-efficiency of container-based gas chemical plants for methanol production in field conditions is considered. The relevance of the direction is determined by the necessity for development of remote Arctic hydrocarbon fields. The object of research is energy-efficient conversion of waste gases energy and surplus thermal energy in small-scale system of methanol production using technology of synthesis gas generation by non-catalytic partial oxidation of natural gas. Approaches to the design and analysis of structural solutions for microturboexpander units are considered. A technique combining traditional approaches to the calculation of equipment and modeling by the finite element method in ANSYS is proposed. The developed methodology facilitates calculation of design parameters for microturboexpanders and allows taking into account peculiarities of working medium, thermobaric conditions and gas flow characteristics.

La1−x(Ce, Sr)xNiO3 perovskite-type oxides as catalyst precursors to syngas production through tri-reforming of methane

LaNiO3 (LN), La0.95Ce0.05NiO3 (LCN) and La0.95Sr0.05NiO3 (LSN) perovskites were synthesized by the polymeric precursor method to act as catalyst precursors for the Tri-reforming of methane (TRM). The majority phase determined for the LCN perovskite was LaNiO3, whereas, for LN and LSN, it was La2NiO4. It was not possible to determine segregated strontium phases for LSN, but LCN presented a small amount of CeO2. All the catalysts presented similar methane conversions (around 75%), however differed in CO2 conversion. LCN was the sample with the highest CO2 conversion (32%), while the values recorded for the LN and LSN samples were 21.9 and 17.1%, respectively. The partial substitution of La3+ by Ce4+ leads to a higher CO2 conversion due to the redox properties of cerium, which promotes CO2 disproportion at the oxygen vacancies generated by cerium, providing more oxygen species that oxidize the coke at the surface. The most active sample for CO2 conversion (LCN) was also the least selective for hydrogen, generating a synthesis gas with an H2/CO ratio of 1.2, while the less active LN and LSN samples were more selective for hydrogen (H2/CO = 1.5–1.6). Thus, it is possible to generate synthesis gas suitable for different applications depending on the metal incorporated into the LaNiO3 perovskite.

Effect of interstitial carbon atoms in core-shell Ni3ZnC0.7/Al2O3 catalyst for high-performance dry reforming of methane

Dry reforming of methane (DRM) on Ni-based catalysts provides an economically and environmentally pivotal route to generate synthesis gas. However, coke formation on Ni surface by the growth of carbon atoms is the main reason for catalyst deactivation and reactor blockage. Here, we propose a reaction-induced method to incorporate and store active carbon atoms into nickel octahedral sites in core-shell Ni3ZnC0.7/Al2O3. This strategy can fundamentally avoid C−C bond formation and feasible oxidation of Ni3ZnC0.7 in low-temperature DRM under CO2-rich condition. About 2 nm of thin-layer Al2O3 encapsulated Ni3ZnC0.7 is explored as the carbon reservoir to accommodate sufficient interstitial carbon atoms, and less than 5% Ni3Zn was observed under CH4/CO2 < 1/1 for 100 h. The dynamic balance of carbon atom storage and conversion in robust Ni3ZnC0.7 contributes to the enhanced activity, stability, coke and oxidation resistance, and distinct reaction pathway in low-temperature DRM.

Biomass Gasification in Downdraft Gasifiers: A Technical Review on Production, Up-Gradation and Application of Synthesis Gas

Rapid climate change and forecasted damage from fossil fuel combustion, forced researchers to investigate renewable and clean energy sources for the sustainable development of societies throughout the world. Biomass-based energy is one of the most important renewable energy sources for meeting daily energy needs, which are gaining in popularity daily. Gasification-based bioenergy production is an effective way to replace fossil fuels and reduce CO2 emissions. Even though biomass gasification has been studied extensively, there is still much opportunity for improvement in terms of high-quality syngas generation (high H2/CO ratio) and reduced tar formation. Furthermore, the presence of tar has a considerable impact on syngas quality. Downdraft gasifiers have recently shown a significant potential for producing high-quality syngas with lower tar concentrations. This article presents a comprehensive review on the advancement in biomass downdraft gasification technologies for high-quality synthesis gas. In addition, factors affecting syngas production and composition e.g., equivalency ratio, temperature, particle size, and gasification medium on synthesis gas generation are also comprehensively studied. The up-gradation and various applications of synthesis gas are also discussed in brief in this review article.

Sandwich Ni-phyllosilicate@doped-ceria for moderate-temperature chemical looping dry reforming of methane

Chemical looping dry reforming of methane (CL-DRM) enables the highly selective oxidation of CH4 and reduction of CO2. We designed sandwich and core-shell structured 5% Ni-SiO2@Ce0.8M0.2O2-δ (M = Fe, Co, Ni) catalysts for moderate-temperature CL-DRM. Highly dispersed nano Ni particles are anchored on the surface of SiO2 spheres, and then transition metal oxide-doped CeO2 is dispersed on the inner core to form a shell layer serving as the oxygen storage role. This trilayer structure provides abundant CeO2-Ni interfaces and catalytic sites. Doping of transition metal oxides helps to activate methane for synthesis gas generation at lower temperatures. In the chemical looping cycle, the available OSC (oxygen storage capacity) was enhanced by the introduction of transition metals into ceria and follows the order of Fe-doped (2.92 mmol g−1) > Ni-doped (1.69 mmol g−1) > Co-doped (0.86 mmol g−1) > undoped (0.58 mmol g−1) catalysts. The catalyst exhibits high coke resistance and redox reactivity in successive CL-DRM redox cycles at 620 °C. In situ Drifts and Raman of CH4/CO2 temperature programmed desorption over recycled/pre-reduced catalysts show that methane is activated into CHx over highly dispersed nickel nanoparticles at 400 °C and then converted into H2 and CO by lattice oxygen. Then, oxygen vacancies are refilled, reduced species (Fe0 and Fe2+) are re-oxidized using CO2 to produce CO, and deposited carbon from CH4 POx is also removed via CO2 gasification.

Pyrolysis Combined with the Dry Reforming of Waste Plastics as a Potential Method for Resource Recovery—A Review of Process Parameters and Catalysts

Emissions of greenhouse gases and growing amounts of waste plastic are serious environmental threats that need urgent attention. The current methods dedicated to waste plastic recycling are still insufficient and it is necessary to search for new technologies for waste plastic management. The pyrolysis-catalytic dry reforming (PCDR) of waste plastic is a promising pro-environmental way employed for the reduction of both CO2 and waste plastic remains. PCDR allows for resource recovery, converting carbon dioxide and waste plastics into synthetic gas. The development and optimization of this technology for the high yield of high-quality synthesis gas generation requires the full understanding of the complex influence of the process parameters on efficiency and selectivity. In this regard, this review summarizes the recent findings in the field. The effect of process parameters as well as the type of catalyst and feedstock are reviewed and discussed.

A highly synergetic method for clean utilization of high-carbon vanadium-bearing stone coal

Aiming at alleviating the difficulties of extracting vanadium from high-carbon stone coal and solving the relevant pollution problem, a new synergetic and cleaner method combining concentration of vanadium with clean utilization of carbon was proposed and corroborated. Firstly, Fe2O3, acting as the source for the catalytic of carbon gasification and the capturer of vanadium, was added to the raw ore. Then, the carbon within the raw ore was gasified by water vapor at 800–900 °C under the catalysis of reducing product of Fe2O3 (Fe3O4) to generate synthesis gas (CO + H2), and subsequently the vanadium dispersive occurred in the ore was captured by Fe3O4 at 1100–1200 °C under Ar atmosphere to form FexV3-xO4. Finally, the FexV3-xO4 phase was separated magnetically, and a high-grade vanadium concentrate was obtained.The experimental results show that the Fe3O4 effectively promoted the gasification rate and ratio of carbon. When 10 mass% Fe2O3 relative to raw ore was added and roasted at 850 °C for 2 h, the gasification ratio of carbon increased by 26%. The gasification ratio of carbon could reach up to 90.2%. Besides, the Fe3O4 could react with the V3+ components to form magnetic V-rich phase, FexV3-xO4, and the vanadium concentrate was obtained by magnetic separation. Under the optimal conditions, the vanadium concentrate with a metallic vanadium content of 6.35 mass% was obtained by magnetic separation, which was 23.5 times higher than the raw ore. The recovery ratio of vanadium reached 85.6%.

C++ Software Program for Downdraft Gasifier Design and Development

Biomass gasification is an important process of converting biomass into a gaseous fuel through a sequence processes of thermochemical reactions. Prototype of down draft gasifier was designed to generate synthesis gas for house hold applications. C++ Software Program for the design and development of downdraft gasification system was done.

Synthesis, redox properties, and catalytic hydrogen gas generation of porphycene cobalt complexes

A new meso-tetrakis(3,5-di-tert-butylphenyl) substituted porphycene and its cobalt complex were synthesized and characterized. Several meso-tetraarylporphycene cobalt complexes having different substituents showed catalytic activity for the hydrogen gas evolution reaction (HER) in the presence of trifluoroacetic acid (TFA) under electrochemical reductive conditions. The electrochemical potential of the HER was -1.50V vs. Ag/AgCl in THF. The active species of this reaction were determined to be the ligand reduced species of Co(II) porphycenes. The catalytic efficiencies of the cobalt complexes of meso-aryl substituted porphycenes and meso-tetraphenylporphyrin were compared and meso-tetraphenyl porphycene cobalt complex exhibited the best current efficiency of 72%. Based on these experimental results and theoretical calculations, we proposed a possible HER mechanism of this system.

Dimethyl ether production from rice straw: process modelling and simulation

Climate change has been a worldwide concern for recently centuries, and exploitation as well as use of fossil fuels dominantly contribute towards the environmental degradation. Several types of alternative energy resources have been taken into account and evaluated in order to find out viable options for the future, and dimethyl ether (DME) is one of those that are worth serious consideration. In this research, a continuous DME production process was developed and simulated using Aspen HYSYSTM. Rice straw, the most popular type of biomass in Vietnam, was chosen to be feedstock for the fuel production. The proposed process consists of five major sections: rice straw pretreatment and gasification for synthesis gas (syngas) generation using a circulating fluidized bed gasifier (CFBG); water-gas shift reaction (WGSR) for H2/CO ratio adjustment in syngas; gas cleaning stage where H2O, H2S and CO2 are removed; DME synthesis via direct production pathway; and DME purification for separation of main product and recycling of methanol. The simulation results indicated a production capacity of approximately 2,307 kg of DME per hour and chemical energy conversion efficiency (ηDME) from biomass into DME of 75%. In addition to that finding, an investigation into the gasifier's operating parameters was conducted for the purpose of maximizing amount of DME generated. From investigation data obtained, the operating temperature of CFBG, steam to biomass (S/B) ratio, and equivalence ratio (ER) that fulfilled such an aim were concluded to be 900oC, 0.27, and 0.32, respectively. This work offers a novel option for utilization of massive availablity of agricultural residues in Vietnam by turning it into a type of promising fuel, and therefore lessen environmental burden as well as may develop Vietnam's energy market.

Thermodynamic Analysis of the Effect of Green Hydrogen Addition to a Fuel Mixture on the Steam Methane Reforming Process

Steam methane (CH4–H2O) reforming in the presence of a catalyst, usually nickel, is the most common technology for generating synthesis gas as a feedstock in chemical synthesis and a source of pure H2 and CO. What is essential from the perspective of further gas use is the parameter describing a ratio of equilibrium concentration of hydrogen to carbon monoxide (H/C=xH2/xCO). The parameter is determined by operating temperature and the initial ratio of steam concentration to methane SC=xH2O0/xCH40. In this paper, the author presents a thermodynamic analysis of the effect of green hydrogen addition to a fuel mixture on the steam methane reforming process of gaseous phase (CH4/H2)–H2O. The thermodynamic analysis of conversion of hydrogen-enriched methane (CH4/H2)–H2O has been performed using parametric equation formalism, allowing for determining the equilibrium composition of the process in progress. A thermodynamic condition of carbon precipitation in methane reforming (CH4/H2) with the gaseous phase of H2O has been interpreted. The ranges of substrate concentrations creating carbon deposition for temperature T = 1000 K have been determined, based on the technologies used. The results obtained can serve as a model basis for describing the properties of steam reforming of methane and hydrogen mixture (CH4/H2)–H2O.