Simulation Analysis of a GTL Process Using Aspen Plus

Gas‐to‐liquid (GTL) processes are becoming attractive due to the increasing price of crude oil. Process simulation analysis on the integrated GTL process is essential as part of an extended process integration analysis of the research subjects. The two sub‐process models for the GTL process, i.e., the syngas generation process and the Fischer Tropsch synthesis (FTS) process, are analyzed in detail with ASPEN Plus. The autothermal reforming process (ATR) is analyzed using Aspen Plus based on the Gibbs reactor model, while FTS is simulated with ASPEN Plus based on detailed kinetic models for industrial iron and cobalt catalysts. Integrated GTL processes with iron and cobalt‐based catalysts were simulated using ASPEN Plus. The optimal flowsheet structures were selected for each catalyst based on the overall performance in terms of thermal and carbon efficiency and product distributions. For the cobalt‐based catalyst, the full conversion concept without CO₂ removal from the FT tail gas is optimal. On the other hand, the once‐through concept with two series reactors and CO₂ removal from raw syngas is considered optimal for the iron‐based catalyst. The thermal efficiency to crude products is likely to be ca. 60 % for the cobalt‐based catalyst, whereas it is in the range of 49–55 % for the iron‐based catalyst. The carbon efficiency using the water‐gas shift reaction is lower using the iron‐based catalyst (61–68 %) than the cobalt‐based catalyst (73–75 %). As expected, the cobalt‐based catalyst is more active and selective, which offers better selectivity towards C₅+ (75–79 %). The selectivity towards C₅+ for the iron‐based catalyst lies in the range 63–75 %.     

High quality diesel via the Fischer–Tropsch process – a review

The Fischer–Tropsch (FT) synthesis is used to produce chemicals, gasoline and diesel fuel. The FT products are predominantly linear, hence the quality of the diesel fuel is very high, having cetane numbers of up to 75. Since purified synthesis gas is used in the FT process all the products are S‐ and N‐free. In this review the production of syngas and the various options used in the FT process (reactors and catalyst types, and high and low temperature operation) are discussed. The best FT option for producing high quality diesel is using cobalt‐based catalyst in slurry phase reactor, gearing the process for high wax production and then selectively hydrocracking the wax to diesel fuel. The overall diesel pool has a high cetane number, the aromatic S and N contents are zero and the exhaust emissions are significantly lower than for standard diesel fuels. © 2001 Society of Chemical Industry     

Increasing carbon utilization in Fischer-Tropsch synthesis using H2-deficient or CO2-rich syngas feeds

Fischer-Tropsch technology has become a topical issue in the energy industry in recent times. The synthesis of linear hydrocarbon that has high cetane number diesel fuel through the Fischer-Tropsch reaction requires syngas with high H₂/CO ratio. Nevertheless, the production of syngas from biomass and coal, which have low H₂/CO ratios or are CO₂ rich may be desirable for environmental and socio-political reasons. Efficient carbon utilization in such H₂-deficient and CO₂-rich syngas feeds has not been given the required attention. It is desirable to improve carbon utilization using such syngas feeds in the Fischer-Tropsch synthesis not only for process economy but also for sustainable development. Previous catalyst and process development efforts were directed toward maximising C₅₊ selectivity; they are not for achieving high carbon utilization with H₂-deficient and CO₂-rich syngas feeds. However, current trends in FTS catalyst design hold the potential of achieving high carbon utilization with wide option of selectivities. Highlights of the current trends in FTS catalyst design are presented and their prospect for achieving high carbon utilization in FTS using H₂-deficient and CO₂-rich syngas feeds is discussed.     

Fischer-Tropsch合成中的CO活化机理

Fischer—Tropsch(F—T)合成是将煤炭、天然气和生物质等含碳资源间接转化为液体燃料的关键工艺步骤,深入了解其反应机理,对于完善F-T合成催化剂设计以及优化其工业操作条件具有重要的理论价值．对近年来有关F—T合成中关键的CO活化机理研究进行了总结和评述,着重介绍了不同过渡金属元素对CO的吸附和活化性质,并就金属晶面与CO的相互作用、催化助剂的影响以及F—T合成反应中与H2的共吸附作用等方面进行分析,为进一步的研究工作提供理     

Microstructured Fischer‐Tropsch Reactor Scale‐up and Opportunities for Decentralized Application

Current projects focusing on the energy transition in traffic will rely on a high‐level technology mix for their commissioning. One of those technologies is the Fischer‐Tropsch synthesis (FTS) that converts synthesis gas into hydrocarbons of different chain lengths. A microstructured packed‐bed reactor for low‐temperature FTS is tested towards its versatility for biomass‐based syngas with a high inert gas dilution. Investigations include overall productivity, conversion, and product selectivity. A 60‐times larger pilot‐scale reactor is further tested. Evaporation cooling is introduced which allows to increase the available energy extraction from the system. From that scale on, an autothermal operation at elevated conversion levels is applicable.     

Novel Natural Gas to Liquids Processes: Process Synthesis and Global Optimization Strategies

An optimization‐based process synthesis framework is proposed for the conversion of natural gas to liquid transportation fuels. Natural gas conversion technologies including steam reforming, autothermal reforming, partial oxidation to methanol, and oxidative coupling to olefins are compared to determine the most economic processing pathway. Hydrocarbons are produced from Fischer–Tropsch (FT) conversion of syngas, ZSM‐5 catalytic conversion of methanol, or direct natural gas conversion. Multiple FT units with different temperatures, catalyst types, and hydrocarbon effluent compositions are investigated. Gasoline, diesel, and kerosene are generated through upgrading units involving carbon‐number fractionation or ZSM‐5 catalytic conversion. A powerful deterministic global optimization method is introduced to solve the mixed‐integer nonlinear optimization model that includes simultaneous heat, power, and water integration. Twenty‐four case studies are analyzed to determine the effect of refinery capacity, liquid fuel composition, and natural gas conversion technology on the overall system cost, the process material/energy balances, and the life cycle greenhouse gas emissions. © 2013 American Institute of Chemical Engineers AIChE J, 59: 505–531, 2013     

碳限域铁基费托合成催化剂研究进展

利用费托合成工艺,将煤、生物质等原料气化产生的合成气转化为液体燃料或化学品,符合我国能源特点和战略需求,而高性能铁基费托合成催化剂的开发能够推动该工艺进步,载体的结构和电子环境会显著影响催化剂的性质。碳材料是铁基费托合成催化剂备受关注的一类载体。本文回顾了不同种类的碳限域载体（包括碳纳米管、介孔碳、有机物衍生、石墨烯等）在费托合成中的最新进展,并重点从几何效应和电子效应两方面阐述了碳材料对铁基费托合成催化剂的限域作用,如对气体扩散和局部浓度、铁物种还原和碳化、碳化铁的相态和晶粒尺寸的稳定性等方面的影响。今后的研究重点是解决催化剂可控制备及碳材料本身在工业操作条件下的稳定性问题,并进一步探明碳包覆结构对碳化铁物相形成和反应机理的影响机制。     

Process synthesis of hybrid coal,biomass, and natural gas to liquids via Fischer–Tropsch synthesis,ZSM-5 catalytic conversion,methanol synthesis,methanol-to-gasoline,and methanol-to-olefins/distillate technologies

Several technologies for synthesis gas (syngas) refining are introduced into a thermochemical based superstructure that will convert biomass, coal, and natural gas to liquid transportation fuels using Fischer–Tropsch (FT) synthesis or methanol synthesis. The FT effluent can be (i) refined into gasoline, diesel, and kerosene or (ii) catalytically converted to gasoline and distillate over a ZSM-5 zeolite. Methanol can be converted using ZSM-5 (i) directly to gasoline or to (ii) distillate via olefin intermediates. A mixed-integer nonlinear optimization model that includes simultaneous heat, power, and water integration is solved to global optimality to determine the process topologies that will produce the liquid fuels at the lowest cost. Twenty-four case studies consisting of different (a) liquid fuel combinations, (b) refinery capacities, and (c) superstructure possibilities are analyzed to identify important process topological differences and their effect on the overall system cost, the process material/energy balances, and the well-to-wheel greenhouse gas emissions.     

Advancement of Fischer‐Tropsch synthesis via utilization of supercritical fluid reaction media

The Fischer Tropsch Synthesis (FTS) reaction has been studied and for nearly a century for the production of fuels and chemicals from nonpetroleum sources. Research and utilization have occurred in both gas phase (fixed bed) and liquid phase (slurry bed) operation. The use of supercritical fluids as the reaction media for FTS (SCF‐FTS) now has a 20‐year history. Although a great deal of progress in SCF‐FTS has been made on the lab scale, this process has yet to be expanded to pilot or industrial scale. This article reviews the research activities involving supercritical FTS and published in open literature from 1989 to 2008. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

清洁燃料的非加氢脱硫技术进展

日益严格的环保法规,对生产低硫、超低硫清洁燃料技术提出了更高要求。介绍了汽柴油脱硫的相关技术,包括加氢脱硫和非加氢脱硫。着重介绍了吸附、氧化和生物脱硫技术进展,同时简要介绍了萃取、膜分离及络合脱硫等工艺。与加氢脱硫相比,非加氢脱硫技术具有操作条件温和、投资及操作费用低等优点,具有更加广阔的发展前景。     

木质纤维素类生物质制取燃料及化学品的研究进展

木质纤维素类生物质含有丰富的纤维素和半纤维素多糖,通过微生物发酵将它们转化为能源及高附加值的化学品,对于缓解全球能源危机带来的压力和解决环境污染问题具有重要意义。介绍了木质纤维素类生物质的结构特征;评述了预处理方法,包括稀酸、高温液态水蒸气爆破、CO2爆破、氨爆、碱法、有机溶剂法、生物处理法;重点介绍由生物质生产乙醇、丁醇及生物柴油的研究现状。指出开发高效环保的预处理方法、构建耐毒高产菌株和应用连续发酵或补料批式发酵方式等是加快木质纤维素类生物质发酵利用工业化进程的关键所在。     

Dominant Reaction Pathways in the Catalytic Partial Oxidation of CH4 on Rh

Reforming technologies are at the heart of converting fossil fuels and biofuels to syngas and hydrogen for novel energy applications and, among reforming technologies, catalytic partial oxidation is appealing for decentralized energy production due to the compactness of reactors. Yet, the mechanisms of these reactions are poorly understood. Here we combine fundamental surface chemistry and detailed reactor models to elucidate the pathways leading to syngas and propose strategies for optimizing the process.     

油页岩与煤路线制油的技术经济分析和比较

液体燃料广泛应用于交通、物流和生活等行业,然而液体燃料的生产严重依赖石油。我国石油资源相对贫乏,石油对外依存度高达60%。为减少对石油的依赖,我国正积极开发石油替代资源,特别是油页岩和煤炭。但迄今少有文献报道对油页岩与煤路线生产液体燃料过程进行全面的技术经济分析和比较。本文通过对油页岩制油和煤制油分别进行建模和模拟,根据模拟从能效、投资和成本等方面对这两种路线进行分析和比较。结果表明油页岩制油的能效比煤制油低5个百分点,因为油页岩制油的原料利用率低,产品收率低。经济方面,油页岩制油的固定投资为63.34元/GJ,相比煤制油节省70%,因为油页岩制油流程短,设备结构简单。但油页岩制油的原料消耗大,生产1t液体燃料消耗24.5t油页岩,所以其成本相比煤制油仅节省6%。     

Automotive fuels from biomass via gasification

There exists already a market of bio-automotive fuels i.e. bioethanol and biodiesel produced from food crops in many countries. From the viewpoint of economics, environment, land use, water use and chemical fertilizer use, however, there is a strong preference for the use of woody biomass and various forest/agricultural residues as the feedstock. Thus, the production of 2nd generation of bio-automotive fuels i.e. synthetic fuels such as methanol, ethanol, DME, FT-diesel, SNG and hydrogen through biomass gasification seems promising. The technology of producing synthetic fuels is well established based on fossil fuels. For biomass, however, it is fairly new and the technology is under development. Starting from the present market of the 1st generation bio-automotive fuels, this paper is trying to review the technology development of the 2nd generation bio-automotive fuels from syngas platform. The production of syngas is emphasized which suggests appropriate gasifier design for a high quality syngas production. A number of bio-automotive fuel demonstration plant will be presented, which gives the state of the art in the development of BTS (biomass to synthetic fuels) technologies. It can be concluded that the 2nd generation bio-automotive fuels are on the way to a breakthrough in the transport markets of industrial countries especially for those countries with a strong forest industry.     

Superstructure optimization of integrated fast pyrolysis‐gasification for production of liquid fuels and propylene

Motivated by the apparent advantages of fast pyrolysis and gasification, a novel integrated biorefinery plant is systematically synthesized for coproducing premium quality liquid fuels and propylene. The required heat and fluidization promotion of the fast pyrolyzer are provided by hot syngas from the gasifier. Light gas and syngas from the fast pyrolyzer are finally converted to hydrocarbons via Fischer‐Tropsch synthesis. Multiple syngas production technologies, hydrocarbon production and downstream upgrading routes are incorporated within a superstructure optimization based process synthesis framework. This is the first article to investigate the benefits associated with the introduction of conventional catalytic cracking and dewaxing from a systems engineering perspective. Surrogate models describing the gasifiers and rigorous equations for Fischer‐Tropsch effluents validated by our experimental collaborator are introduced. Through investigation of five scenarios the primary parameters affecting overall economic performance are identified through ranking of the relevant candidates. Comparisons of the hybrid conversion route and stand‐alone routes are made. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3155–3176, 2016     

Incorporation of catalytic dehydrogenation into Fischer-Tropsch synthesis of liquid fuels from coal to minimize carbon dioxide emissions

Synthesis gas (syngas) produced from coal typically has hydrogen to carbon monoxide ratios in the range of approximately 0.7-1.1, depending on the gasification method. In order to produce liquid fuels from this syngas by Fischer-Tropsch synthesis (FTS), these ratios must be raised to 2.0 or higher. If this is accomplished by the water-gas shift reaction, the traditional method, large emissions of carbon dioxide are produced. In this paper, it is shown that catalytic dehydrogenation (CDH) of the gaseous C1-C4 products of FT synthesis and recycling of the resulting hydrogen to the syngas feed-stream can increase the H₂/CO ratio to the desired values with little or no production of carbon dioxide. All carbon from the CDH reaction is in the form of a potentially valuable by-product, multi-walled carbon nanotubes (MWCNT). The amounts of hydrogen and MWCNT produced, carbon dioxide emissions avoided, and water saved are calculated for a 50,000 bbl/day FTS-CDH plant and it is demonstrated that the energy balance for the process is favorable. Methods of utilizing the large quantity of MWCNT produced are discussed.     

Controllable Fe/HCS catalysts in the Fischer-Tropsch synthesis: Effects of crystallization time

The Fischer–Tropsch synthesis (FTS) continues to be an attractive alternative for producing a broad range of fuels and chemicals through the conversion of syngas (H₂ and CO), which can be derived from various sources, such as coal, natural gas, and biomass. Among iron carbides, Fe₂C, as an active phase, has barely been studied due to its thermodynamic instability. Here, we fabricated a series of Fe₂C embedded in hollow carbon sphere (HCS) catalysts. By varying the crystallization time, the shell thickness of the HCS was manipulated, which significantly influenced the catalytic performance in the FTS. To investigate the relationship between the geometric structure of the HCS and the physic-chemical properties of Fe species, transmission electron microscopy, X-ray diffraction, N₂ physical adsorption, X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction, Raman spectroscopy, and Mössbauer spectroscopy techniques were employed to characterize the catalysts before and after the reaction. Evidently, a suitable thickness of the carbon layer was beneficial for enhancing the catalytic activity in the FTS due to its high porosity, appropriate electronic environment, and relatively high Fe₂C content.     

Influence of Reaction Conditions on the Conversion of Methane‐Rich Gases to Fischer‐Tropsch Products

Evidence is provided that stable operation of a microstructured reactor for steam‐assisted catalytic partial oxidation (sCPOX) and its subsequent coupling with a Fischer‐Tropsch synthesis (FTS) reactor is possible at pressures up to 25 bar. The product composition of the sCPOX was determined and subsequently used as feed composition for a downstream FTS reactor to prove the possibility of coupling with syngas generation. After stable operation was proven in both setups, they were coupled and operated together, feeding the product gas stream of the sCPOX to the FTS. In addition, the negative influence of sulfur in the sCPOX‐gas feed was evaluated.     

Syngas production through gasification and cleanup for downstream applications — Recent developments

In the present paper various gasification technologies/gasifiers and syngas cleaning options are critically reviewed keeping in view various types of feedstocks and various downstream applications of syngas such as power generation, chemicals and hydrogen production, liquid fuels production and synthetic natural gas (SNG) production. Recent developments on gasification technologies including fixed bed dry bottom (FBDB) gasification, power high temperature Winkler (PHTW) gasification, catalytic steam gasification, transport reactor gasifier as well as syngas cleanup technique including hot gas filter and warm cleaning are discussed. Techno-economic analysis of various gasifiers as well as syngas cleaning processes along with the world scenario of syngas production and its various downstream applications is also discussed.     

An overview of new approaches to deep desulfurization for ultra-clean gasoline, diesel fuel and jet fuel

This review discusses the problems of sulfur reduction in highway and non-road fuels and presents an overview of new approaches and emerging technologies for ultra-deep desulfurization of refinery streams for ultra-clean (ultra-low-sulfur) gasoline, diesel fuels and jet fuels. The issues of gasoline and diesel deep desulfurization are becoming more serious because the crude oils refined in the US are getting higher in sulfur contents and heavier in density, while the regulated sulfur limits are becoming lower and lower. Current gasoline desulfurization problem is dominated by the issues of sulfur removal from FCC naphtha, which contributes about 35% of gasoline pool but over 90% of sulfur in gasoline. Deep reduction of gasoline sulfur (from 330 to 30 ppm) must be made without decreasing octane number or losing gasoline yield. The problem is complicated by the high olefins contents of FCC naphtha which contributes to octane number enhancement but can be saturated under HDS conditions. Deep reduction of diesel sulfur (from 500 to <15 ppm sulfur) is dictated largely by 4,6-dimethyldibenzothiophene, which represents the least reactive sulfur compounds that have substitutions on both 4- and 6-positions. The deep HDS problem of diesel streams is exacerbated by the inhibiting effects of co-existing polyaromatics and nitrogen compounds in the feed as well as H₂S in the product. The approaches to deep desulfurization include catalysts and process developments for hydrodesulfurization (HDS), and adsorbents or reagents and methods for non-HDS-type processing schemes. The needs for dearomatization of diesel and jet fuels are also discussed along with some approaches. Overall, new and more effective approaches and continuing catalysis and processing research are needed for producing affordable ultra-clean (ultra-low-sulfur and low-aromatics) transportation fuels and non-road fuels, because meeting the new government sulfur regulations in 2006–2010 (15 ppm sulfur in highway diesel fuels by 2006 and non-road diesel fuels by 2010; 30 ppm sulfur in gasoline by 2006) is only a milestone. Desulfurization research should also take into consideration of the fuel-cell fuel processing needs, which will have a more stringent requirement on desulfurization (e.g., <1 ppm sulfur) than IC engines. The society at large is stepping on the road to zero sulfur fuel, so researchers should begin with the end in mind and try to develop long-term solutions.