Power- and resource-saving process for producing methanol from natural gas

The processes for producing methanol from syngas and syngas from natural gas are simulated. A kinetic model for the reaction of steam-carbon dioxide reforming of methane that is in good agreement with the experimental data obtained for the ranges of gas hourly gas velocities of 1000 to 10000 h^?1, temperatures of 700 to 850°C, and pressures of 0.4 to 2.0 MPa is developed. A power-and resource-saving process flowsheet for the production of methanol at a variable pressure in the catalytic reactors is proposed. Methods of intensifying an industrial methanol synthesis process with an end-product output of 60000 tons per year are developed. It is shown that when the carbon dioxide formed in the reaction of steam reforming of methane is recycled to the feed, the methanol output can be increased up to 72000 tons per year.     

An efficient technique for improving methanol yield using dual CO2 feeds and dry methane reforming

Steam methane reforming (SMR)-based methanol synthesis plants utilizing a single CO₂ feed represent one of the predominant technologies for improving methanol yield and CO₂ utilization. However, SMR alone cannot achieve full CO₂ utilization, and a high water content accumulates if CO₂ is only fed into the methanol reactor. In this study, a process integrating SMR with dry methane reforming to improve the conversion of both methane and CO₂ is proposed. We also propose an innovative methanol production approach in which captured CO₂ is introduced into both the SMR process and the recycle gas of the methanol synthesis loop. This dual CO₂ feed approach aims to optimize the stoichiometric ratio of the reactants. Comparative evaluations are carried out from a techno-economic point of view, and the proposed process is demonstrated to be more efficient in terms of both methanol productivity and CO₂ utilization than the existing stand-alone natural gas-based methanol process.     

甲醇合成影响因素与粗甲醇中乙醇含量超标研究

操作条件、入塔气组成以及催化剂性能是影响甲醇合成反应的主要因素。文章对甲醇合成反应的影响因素进行分析,找出甲醇装置开车初期粗甲醇中乙醇含量超标的具体原因,并在此基础上进行优化操作,粗甲醇中乙醇含量达到或优于设计指标。     

影响甲醇合成催化剂时空收率的因素

研究温度、压力、空速、原料气组成等对甲醇合成催化剂时空收率的影响 ,以及催化剂使用前后的时空收率 ,CO、 CO2 转化率 ,粗甲醇含水量 ,粗甲醇中杂质的变化规律。并对实验结果进行了数学关联和综合分析     

Membrane/sorption-enhanced methanol synthesis process: Dynamic simulation and optimization

In this study, a dynamic mathematical model of a Membrane-Gas-Flowing Solids-Fixed Bed Reactor (Membrane-GFSFBR) with in-situ water adsorption in the presence of catalyst deactivation is proposed for methanol synthesis. The novel reactor consists of water adsorbent and hydrogen-permselective Pd-Ag membrane. In this configuration feed gas and flowing adsorbents are both fed into the outer tube of the reactor. Contact of gas and fine solids particles inside packed bed results in selective adsorption of water from methanol synthesis which leads to higher methanol production rate. Afterwards, the high pressure product is recycled to the inner tube of the reactor and hydrogen permeates to the outer tube which shifts the reaction towards more methanol production. Dynamic simulation result reveals that simultaneous application of water adsorbent and hydrogen permeation in methanol synthesis process contributes to a significant enhancement in methanol production. The notable advantage of Membrane-GFSFBR is the continuous adsorbent regeneration during the process. Moreover, a theoretical investigation has been performed to evaluate the optimal operating conditions and to maximize the methanol production in Membrane-GFSFBR using differential evolution (DE) algorithm as a robust method. The obtained optimization result shows there are optimum values of inlet temperatures of gas phase, flowing solids phase, and shell side under which the highest methanol production can be achieved.     

Liquid phase methanol and dimethyl ether synthesis from syngas

The Liquid Phase Methanol Synthesis (LPMeOH^TM) process has been investigated in our laboratories since 1982The reaction chemistry of liquid phase methanol synthesis over commercial Cu/ZnO/Al₂O₃ catalysts, established for diverse feed gas conditions including H₂-rich, CO-rich, CO₂-rich, and CO-free environments, is predominantly based on the CO₂ hydrogenation reaction and the forward water-gas shift reactionImportant aspects of the liquid phase methanol synthesis investigated in this in-depth study include global kinetic rate expressions, external mass transfer mechanisms and rates, correlation for the overall gas-to-liquid mass transfer rate coefficient, computation of the multicomponent phase equilibrium and prediction of the ultimate and isolated chemical equilibrium compositions, thermal stability analysis of the liquid phase methanol synthesis reactor, investigation of pore diffusion in the methanol catalyst, and elucidation of catalyst deactivation/regenerationThese studies were conducted in a mechanically agitated slurry reactor as well as in a liquid entrained reactorA novel liquid phase process for co-production of dimethyl ether (DME) and methanol has also been developedThe process is based on dual-catalytic synthesis in a single reactor stage, where the methanol synthesis and water gas shift reactions takes place over Cu/ZnO/Al₂O₃ catalysts and the in-situ methanol dehydration reaction takes place over -Al₂O₃ catalystCo-production of DME and methanol can increase the single-stage reactor productivity by as much as 80%. By varying the mass ratios of methanol synthesis catalyst to methanol dehydration catalyst, it is possible to co-produce DME and methanol in any fixed proportion, from 5% DME to 95% DMEAlso, dual catalysts exhibit higher activity, and more importantly these activities are sustained for a longer catalyst on-stream life by alleviating catalyst deactivation.     

甲醇合成路线的新进展

近些年来，国内外对甲醇合成路线的改进及新合成路线的开拓取得很大进展。本文从合成气的生产方法、气相合成、液相合成及甲烷直接转化法等几方面综述了国外最新动态。     

合成氨联产甲醇工艺的进展

合成氨联产甲醇工艺是20世纪60年代我国开发的具有自主产权的新工艺。在醇氨质量比约20%时,吨氨成本下降约30元。90年代开发的甲醇化甲烷化工艺是合成氨工业史上一大变革。在醇氨质量比为20%时,吨氨成本可下降80元左右。目前正在开发的合成氨联产甲醇技术与其他净化技术———吸附法净化技术组合的新工艺,其能耗只约占甲烷化工艺能耗的20%。原料气经吸附脱除少量CO2、CO和水后不经氨冷器直接进入氨合成塔,既节省能耗又提高装置能力,若这一成果能实现工业化,将是合成氨工艺一项新进展。     

甲醇合成路线及其进展

介绍了甲醇合成的各种路线及其最新进展。合成气合成甲醇是现行的主要工艺路线 ,而甲烷氧化法、二氧化碳加氢法是甲醇合成路线的研究热点。     

Liquid-phase synthesis of methanol using industrial copper-zinc catalyst

The industrial copper-zinc catalyst MEGAMAX®-phase synthesis of methanol was tested under the conditions of a liquid-phase process while varying the pressure (0.5–7.0 MPa) and the gas mixture flow rate (40–400 mL_N/min). The catalyst was shown to have high activity and selectivity in the synthesis of methanol. The best result (730 g(methanol)/kg(cat) h^?1 and selectivity 99.2%) was obtained under reaction conditions of 2.0 MPa, 240°C, H₂: CO: CO₂: N₂ = 70.5: 17.9: 6.5: 5.1, and reaction time 3 h. The concentration of methane by-product increased at gas mixture pressures over 3.0 MPa, lowering the selectivity of the process with respect to methanol. Trace amounts of ethane and water were found in addition to methane. Dimethyl ether, a typical by-product of methanol synthesis, was missing from the vapor-gas mixture over the range of pressures. The results from this study indicate that the MEGAMAX® can be used in the liquid-phase synthesis of methanol.     

合成甲醇催化剂的新进展

综述了合成甲醇的低温液相合成法、甲烷催化氧化法和二氧化碳催化加氢法等新工艺所使用的催化剂及其活性中心、催化反应条件和反应机理的研究近况。与传统的合成气合成甲醇技术相比 ,在催化剂性能、原料成本及发展前景等诸方面各有优点 ,提倡大力开发以二氧化碳或甲烷生产甲醇的绿色化学新工艺。     

Investigation on and industrial application of degrading of methanol feed in methanol to propylene process

At present, methanol to propylene (MTP) technology developed by Lurgi Company is adopted for commercial plants and refined methanol with the purity ≥ 99.85 wt% is required as the feed of MTP unit in Lurgi's technology. Therefore, high energy cost for refined methanol production is one of the bottlenecks to improve the economy of MTP technology. Reducing the grade of feed refined methanol may be an effective method to save energy and reduce operation costs in MTP process. In this work, experiments and process simulation were carried out to investigate the influence and feasibility of degrading the methanol feed. Experiments were conducted to investigate the influence of crude methanol feed on conversion and selectivity of MTP reaction as well as the performance of ZSM-5 catalyst. The experimental results showed that degrading the methanol feed had no obvious influence on the conversion and selectivity of MTP reactions and the catalyst deactivation was caused by the carbon accumulation and metals deposition on the active sites. The process simulation results showed that the influence on the conversion and selectivity as well as the stream load of MTP process was negligible if 98mol% methanol was used as feed. Finally, industrial experiments were conducted by adjusting the operation parameters to degrade of feed methanol of the commercial 500 kt·a^-1 MTP unit of Ningmei Group in China. The results of industrial application illustrated that annually 180 kt fuel coal and 150 kt desalted water as well as1770 MW·h^-1 electricity would be saved when the water content increased from 0.01% to 0.4%. This work has identified the feasibility to improve MTP technology by degrading the methanol feed.     

Contribution to emission reduction of CO2 by a fluidized-bed membrane dual-type reactor in methanol synthesis process

In this work, a fluidized-bed membrane dual-type reactor was evaluated for CO₂ removal in methanol synthesis process. The feed synthesis gas is preheated in the tubes of the gas-cooled reactor and flowing in a counter-current mode with reacting gas mixture in the shell side. Due to the hydrogen partial pressure driving force, hydrogen can penetrate from feed synthesis gas into the reaction side through the membrane. The outlet synthesis gas from this reactor is fed to tubes of the water-cooled packed-bed reactor and the chemical reaction is initiated by the catalyst. The methanol-containing gas leaving this reactor is directed into the shell of the gas-cooled reactor and the reactions are completed in this fluidized-bed side. A two-phase dynamic model in bubbling regime of fluidization was developed in the presence of long-term catalyst deactivation. This model is used to compare the removal of CO₂ in a FBMDMR with a conventional dual-type methanol synthesis reactor (CDMR) and a membrane dual-type methanol synthesis reactor (MDMR). The simulation results show a considerable enhancement in the CO₂ conversion due to have a favourable profile of temperature and activity along the fluidized-bed membrane dual-type reactor relative to membrane and conventional dual-type reactor systems.     

Comparison of two-phase and three-phase methanol synthesis processes

A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The basic kinetic and thermodynamic data were taken from previous studies carried out in our laboratory. The results show that both reactor systems produce comparable methanol yields under the same process conditions except for the reactor temperature. Carbon conversion to methanol values close to 100% can be achieved. The three-phase process is more efficient in terms of heat recovery and power consumption. This is primarily caused by the fact that the three-phase process generates high-pressure steam and the ICI two-phase process yields boiler feed water of 90°C. Furthermore, the pressure drop in the three-phase reactor is smaller than in the two-phase reactor, resulting in a smaller duty of the recycle compressor. However, for the present low energy prices, the annual financial savings, coupled with these energetic aspects, are not sufficient to compensate for the higher capital investment of the three-phase reactor system relative to the ICI two-phase reactor system. A relatively high natural gas price of US $4.1 per gigajoule is needed to reach the economical break-even point between the two processes. More active catalysts may be developed in the near future. Our results show that a relative increase in the catalyst activity by a factor of 1.5 or more (for both processes) will make the three-phase process of economic interest at a natural gas price of US $2.5 per gigajoule.     

Pervaporation separation of methyl tert-butyl ether/methanol mixtures using a high-performance blended membrane

For the separation of methyl tert-butyl ether (MTBE) and methanol mixtures, we investigated the pervaporation performance of a blend membrane made from cellulose acetate and cellulose acetate hydrogen phthalate. At first the influence of the blend composition was studied with a certain feed mixture. We found that all the tested membranes permeate methanol preferentially. The selectivity increases and the permeation rate decreases with increasing cellulose acetate content in the blend. Therefore, an optimal blend composition of 30 wt % in cellulose acetate was chosen to evaluate the influence of the feed composition and the experimental temperature on the pervaporation performance. When the feed temperature or the methanol content in the feed increases, the permeation rates are greatly enhanced and the selectivity decreases. However, the temperature effect is more significant at low methanol content in the feed and becomes negligible at high methanol content in the feed where plasticity effects prevail. A comparison, carried out with all the membranes until now used for the separation of MTBE/methanol mixtures, showed that the blended membrane studied in this present work presents good permselective properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 875–882, 1997     

Hydrogen production by the catalytic steam reforming of methanol part 1: The thermodynamics

The thermodynamic equilibria involved in the catalytic steam reformation of methanol to produce hydrogen have been examined over the ranges of pressure 101–3040 kPa, temperature 400–700K and water to methanol feed ratio 1.5–0.67. Four models have been considered based upon possible reaction products and the equilibrium composition of each model calculated. The presence of methane and carbon reduce the quantity and quality of hydrogen produced. The best condition for hydrogen production occurs at 500K in the model in which carbon (soot) and methane gas are excluded and where pressures are low, and water is in excess in the feed. To achieve these conditions in practice the reactions for methane formation, which is thermodynamically favoured, and the appearance of carbon (soot) must be inhibited.     

Synthesizing methanol from nitrogen-ballasted syngas

The possibility of the effective catalytic synthesis of methanol from nitrogen-ballasted syngas was studied. Syngas was obtained during the operation of power machines such as diesel engines or gas turbines. The dependences of CO and CO₂ conversion per cycle, the quality of methanol, et cetera on the composition of syngas are characterized. The kinetic dependences of methanol synthesis on G-79-7GL catalyst (Zud Chemie) are described. For nitrogen-ballasted syngas, the dependences of the CO and CO₂ conversion and the output and quality of methanol on the reaction conditions (pressure, temperature, and gas mixture feed rate) are the same as for nitrogen-free syngas, though the CO conversion declined considerably when the concentration of ballast nitrogen was increased. These studies served as the basis for the creation of energy-independent units for processing hydrocarbon gases into methanol and motor fuels.     

净化黄磷尾气部分变换制甲醇合成气中试研究

在40 m3/h部分变换中试装置上,采用铁铬系中温变换催化剂,以净化黄磷尾气为原料,经部分变换工艺直接制取甲醇合成气。研究结果表明:以净化黄磷尾气燃烧气为升温介质,负压和循环升温相结合是可行的升温与还原方法;催化剂宜采用二段填装;在汽/气体积流量比1.35—1.40、催化剂床层入口温度310—320℃、原料气流量30—32 m3/h的条件下可获得H2/CO体积流量比合格的甲醇合成气;催化剂床层平均温度随入口温度、蒸汽量和原料气量的增加而升高;中试装置连续运行130 h,合成气中H2/CO摩尔比1.87—3.40。     

甲醇作为催化裂化部分进料的反应过程

基于甲醇制低碳烯烃（MTO）与催化裂化（FCC）反应及工艺过程的分析、比较,提出二者结合的可能性,将甲醇作为FCC部分进料用以增产低碳烯烃.根据FCC过程特点,通过实验考察反应温度、甲醇水溶液、积炭催化剂等因素对甲醇转化的影响;验证了甲醇在FCC条件下可具有较高的低碳烯烃产率.实验结果表明：在40％(质量分数)甲醇水溶液进料、未积炭催化剂、反应温度550～600℃的条件下,甲醇转化的烃产率可达26.3%～28.1％(质量分数),低碳烯烃占烃组成的67.8%～66.5％(质量分数).同时对甲醇在FCC条件下的反应特点进行了初步分析.研究结果为进一步实现甲醇作为FCC部分进料提供了重要依据.     

C306型低压甲醇合成催化剂应用小结

介绍了C30 6型低压甲醇合成催化剂在以天然气为原料合成甲醇装置上的使用情况 ,通过测试 ,对C30 6型催化剂的使用效果作出了评价