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Kinetic study of the methanol to olefin process on a SAPO-34 catalyst

Mehdi SEDIGHI,Kamyar KEYVANLOO

《化学科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 306-311 doi: 10.1007/s11705-014-1440-z

摘要: In this paper, a new kinetic model for methanol to olefin process over SAPO-34 catalyst was developed using elementary step level. The kinetic model fits well to the experimental data obtained in a fixed bed reactor. Using this kinetic model, the effect of the most important operating conditions such as temperature, pressure and methanol space-time on the product distribution has been examined. It is shown that the temperature ranges between 400 °C and 450 °C is appropriate for propene production while the medium temperature (450 °C) is favorable for total olefin yield which is equal to 33%. Increasing the reactor pressure decreases the ethylene yield, while medium pressure is favorable for the propylene yield. The result shows that the ethylene and propylene and consequently the yield of total olefins increase to approximately 35% with decreasing the molar ratio of inlet water to methanol.

关键词: methanol to olefin     SAPO-34     kinetic modeling     elementary step    

Acid resistance of methanogenic bacteria in a two-stage anaerobic process treating high concentrationmethanol wastewater

ZHOU Xuefei, REN Nanqi

《环境科学与工程前沿(英文)》 2007年 第1卷 第1期   页码 53-56 doi: 10.1007/s11783-007-0010-8

摘要: In this study, the two-stage upflow anaerobic sludge blanket (UASB) system and batch experiments were employed to evaluate the performance of anaerobic digestion for the treatment of high concentration methanol wastewater. The acid resistance of granular sludge and methanogenic bacteria and their metabolizing activity were investigated. The results show that the pH of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor. Apparently, these were not the advisable pH levels that common methanogenic bacteria could accept. The methanogenic bacteria of the system, viz. Methanosarcina barkeri, had some acid resistance and could still degrade methanol at pH 5.0. If the methanogenic bacteria were trained further, their acid resistance would be improved somewhat. Granular sludge of the system could protect the methanogenic bacteria within its body against the impact of the acidic environment and make them degrade methanol at pH 4.5. The performance of granular sludge was attributed to its structure, bacteria species, and the distribution of bacterium inside the granule.

关键词: pH     Granular     upflow anaerobic     advisable pH     methanogenic    

Simulation analysis of methanol flash distillation circulation process in biodiesel production with supercritical

Zhengjiao TANG, Cunwen WANG, Weiguo WANG, Jia GUO, Yuanxin WU, Jinfang CHEN, Yigang DING

《能源前沿(英文)》 2011年 第5卷 第1期   页码 93-97 doi: 10.1007/s11708-010-0028-7

摘要: High methanol-to-oil ratio is required to obtain a high conversion of oil for the production of biodiesel with supercritical methanol. Recovering the methanol of a stream issuing from a transesterification supercritical reactor by flash distillation instead of evaporation was analyzed. The one-stage and two-stage flash distillation processes were presented and compared. The difference of the recovery percentage of methanol of the above two flash processes is less than 0.5% and the methanol concentration in the vapor for the one-stage process decreases rapidly when feed temperature increases. The process in which the product of transesterification of soybean oil with supercritical methanol is cooled to an appropriate temperature (about 240°C) first and then flashed was put forward. The effect of cooling temperature, feed pressure and flash pressure on methanol concentration and recovery percentage was investigated. According to this study, when the feed pressure range is 15–30 MPa, the flash pressure equals 0.4 MPa, and cooling temperature range is 240°C–250°C, the recovery percentage of methanol is not less than 85%, and the concentration of the vapor in mass fraction of methanol is approximately 99%. Thus, the vapor leaving the flash tank can be directly circulated to the transesterification reactor.

关键词: supercritical methanol     biodiesel     recovery     flash distillation    

An efficient technique for improving methanol yield using dual CO

Yang Su, Liping Lü, Weifeng Shen, Shun’an Wei

《化学科学与工程前沿(英文)》 2020年 第14卷 第4期   页码 614-628 doi: 10.1007/s11705-019-1849-5

摘要: Abstract 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.

关键词: methanol synthesis     CO2 utilization     dry methane reforming     steam methane reforming     process design    

High-precision diffusion measurement of ethane and propane over SAPO-34 zeolites for methanol-to-olefinprocess

Dali Cai, Yu Cui, Zhao Jia, Yao Wang, Fei Wei

《化学科学与工程前沿(英文)》 2018年 第12卷 第1期   页码 77-82 doi: 10.1007/s11705-017-1684-5

摘要: The methanol-to-olefin (MTO) process has attracted much attention and many problems including lifetime and selectivity of light olefins have all been connected to the diffusion problems in zeolite crystals. However, a quantitative study of diffusion problems in SAPO-34 zeolites is lacking. In this paper, we performed a high-precision diffusion measurement of the diffusion behavior of ethane and propane, which represent ethylene and propylene respectively, over SAPO-34. The diffusions of ethane and propane over fresh and coked SAPO-34 zeolites with different crystal sizes were carefully studied. Ethane and propane show different diffusion behavior in SAPO-34. The diffusion of ethane is almost not influenced by the crystal size and coke percentage, whereas that of propane is strongly affected. A slower diffusion velocity was observed in bigger crystals, and the diffusion velocity decline significantly with the coke percentage increasing. The diffusion coefficient was calculated with both the internal and surface diffusion models, and the results show that the surface diffusion plays a key role in the diffusion process of both ethane and propane. We believe that this work would be helpful for understanding the diffusion of different molecules in SAPO-34 zeolites, and may lay the foundation of MTO research.

关键词: diffusion measurement     methanol-to-olefin process    

Anaerobic treatment of wastewater containing methanol in up-flow anaerobic sludge bed (UASB) reactor

LIN Yishan, HE Yanling, MENG Zhuo, YANG Shucheng

《环境科学与工程前沿(英文)》 2008年 第2卷 第2期   页码 241-246 doi: 10.1007/s11783-008-0040-x

摘要: The direct conversion of methanol into methane is the main process in anaerobic treatment of methanol containing wastewater. However, acetic acid can also be produced from methanol theoretically, which may probably result in an abrupt pH drop and deteriorate the anaerobic process. Therefore, it is interesting to know what would really happen in an anaerobic reactor treating methanol wastewater. In this study, an up-flow anaerobic sludge bed (UASB) reactor treating methanol wastewater was operated. The chemical oxygen demand (COD), acetic acid and pH of the effluent were monitored at different loadings and influent alkalinity. The results showed that the anaerobic reactor could be operated steadily at as low as 119 mg/L of influent alkalinity and high organic loading rate with no obvious pH drops. Volatile fatty acids accumulation was not observed even at strong shock loadings. The microorganisms in the sludge at the end of the test became homogeneous in morphology, which were mainly spherical or spheroidal in shape.

关键词: homogeneous     spherical     influent alkalinity     process     anaerobic treatment    

Process synthesis with simultaneous consideration of inherent safety-inherent risk footprint

Andreja Nemet, Jiří J. Klemeš, Zdravko Kravanja

《化学科学与工程前沿(英文)》 2018年 第12卷 第4期   页码 745-762 doi: 10.1007/s11705-018-1779-7

摘要:

Process plants should be designed to be economically viable and environmentally friendly, while also being operable and maintainable during process implementation. The safety of processes is among the most important considerations in obtaining results that are more acceptably realistic, as it is linked to the availability and reliability of the process. Inherent safety can effectively be enhanced in the early stages of the design, when the main decisions on process design are made. The aim of this study is to enhance and select the appropriate risk assessment method and to incorporate it into process synthesis, using a mathematical programming approach. A mixed-integer, nonlinear programming (MINLP) model was used for the synthesis of a methanol production process, considering risk assessment during the synthesis. Risk assessment is performed simultaneously with the MINLP process synthesis, where the risk is determined either for the whole process as overall risk, or on a per unit-of-a-product basis. For the latter, a new measurement is proposed: the inherent risk footprint. The results of a case study led to two main conclusions: (i) Significantly safer designs can be obtained at negligible economic expense, and (ii) at higher production capacities, a lower inherent risk footprint can be achieved. The results also indicate that designs obtained using this method can have significantly increased inherent safety, while remaining economically viable.

关键词: inherent safety     process design     simultaneous risk assessment     risk footprint     methanol process    

Impacts of methanol fuel on vehicular emissions: A review

《环境科学与工程前沿(英文)》 2022年 第16卷 第9期 doi: 10.1007/s11783-022-1553-4

摘要:

● Methanol effectively reduces CO, HC, CO2, PM, and PN emissions of gasoline vehicles.

关键词: Methanol fuel     Vehicular emission     Emission reduction     Cleaner fuel     Gasoline substitute    

Confinement effects in methanol to olefins catalysed by zeolites: A computational review

German Sastre

《化学科学与工程前沿(英文)》 2016年 第10卷 第1期   页码 76-89 doi: 10.1007/s11705-016-1557-3

摘要: Small pore zeolites, containing 8-rings as the largest, are widely employed as catalysts in the process of methanol-to-olefins (MTO). Reactants and products diffuse with constraints through 8-rings and this is one of the reaction bottlenecks related to zeolite micropore topology. Small pore zeolites and silicon-aluminophosphates(SAPOs) containing cavities, where olefins are mainly formed through the hydrocarbon pool (HP) mechanism, are frequently tested for MTO. Shape selectivity of transition states within the side-chain methylation will be reviewed as this is one of the controlling steps of the MTO process, with particular attention to the role of hexamethylbenzene (HMB) and heptamethylbenzenium cation (HeptaMB ), which are the most tipically detected reaction intermediates, common to the paring and side-chain routes within the HP mechanism. The relative stability of these and other species will be reviewed in terms of confinement effects in different cage-based zeolites. The role of the different alkylating agents, methanol, dimethyl ether (DME), and surface methoxy species (SMS) will also be reviewed from the computational viewpoint.

关键词: small pore zeolites     SAPOs     methanol-to-olefins     hydrocarbon pool mechanism     alkylation of polymethylbenzenes    

Hydrogen production from methanol through dielectric barrier discharge

Baowei WANG, Xu ZHANG, Haiying BAI, Yijun Lü, Shuanghui HU

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 209-214 doi: 10.1007/s11705-010-1018-3

摘要: The hydrogen fuel cell is a promising option as a future energy resource and the production of hydrogen is mainly depended on fossil fuels now. In this paper, methanol reforming to produce H through dielectric-barrier discharge (DBD) plasma reaction was studied. Effects of the power supply parameters, reactor parameters and process conditions on conversion of methanol and distribution of products were investigated. The best reaction conditions were following: input power (45 W), material of inner electrode (stainless steel), discharge gap (3.40 mm), length of reaction zone (90.00 mm), dielectric thickness (1.25 mm), and methanol content (37.65%). The highest conversion of methanol and the yield of H were 82.38% and 27.43%, respectively.

关键词: methanol     dielectric-barrier discharge     hydrogen     plasma    

Experimental study on premixed combustion of spherically propagating methanol-air-nitrogen flames

Xiangang WANG, Zhiyuan ZHANG, Zuohua HUANG, Xibin WANG, Haiyan MIAO,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 223-233 doi: 10.1007/s11708-010-0016-y

摘要: The outward propagation and development of surface instability of the spark-ignited spherical premixed flames for methanol-air-nitrogen mixtures were experimentally studied by using a constant volume combustion chamber and a high-speed schlieren photography system. The laminar burning velocities, the mass burning fluxes, and the Markstein lengths were obtained at different equivalence ratios, dilution ratios, initial temperatures, and pressures. The laminar burning velocities and the mass burning fluxes give a similar curve versus the equivalence ratios. They increase with the increase of initial temperature and decrease with the increase of dilution ratio. The laminar burning velocity decreases with elevating the initial pressure, while the mass burning flux increases with the increase of the initial pressure. Markstein length decreases slightly with the increase of initial temperature for the rich mixtures. High initial pressure corresponds to low Markstein length. Markstein length increases with the increase of dilution ratio, which is more obvious when the mixture becomes leaner. Equivalence ratio has a slight impact on the development of the diffusive-thermal cellular structure at elevated initial pressures. The initial pressure has a significant influence on the occurrence of the flame front cellular structure. At the elevated pressures, the cracks on the flame surface branch and develop into the cell structure. These cells are bounded by cracks emitting a bright light, which may indicate soot formation. For very lean mixture combustion, the buoyancy effect and cooling effect from the spark electrodes have a significant impact on the flame propagation. The hydrodynamic instability, inhibited with the increase of initial temperature around the stoichiometric equivalence ratio, is enhanced with the increase of initial pressure and suppressed by mixture dilution.

关键词: methanol     spherical flame     propagation characteristics     flame instabilities    

Mechanism of methanol decomposition on the Pd/WC(0001) surface unveiled by first-principles calculations

Jinhua Zhang, Yuanbin She

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 1052-1064 doi: 10.1007/s11705-019-1908-y

摘要: In this study, the decomposition of methanol into the CO and H species on the Pd/tungsten carbide (WC)(0001) surface is systematically investigated using periodic density functional theory (DFT) calculations. The possible reaction pathways and intermediates are determined. The results reveal that saturated molecules, i.e., methanol and formaldehyde, adsorb weakly on the Pd/WC(0001) surface. Both CO and H prefer three-fold sites, with adsorption energies of ‒1.51 and ‒2.67 eV, respectively. On the other hand, CH O stably binds at three-fold and bridge sites, with an adsorption energy of ‒2.58 eV. However, most of the other intermediates tend to adsorb to the surface with the carbon and oxygen atoms in their sp and hydroxyl-like configurations, respectively. Hence, the C atom of CH OH preferentially attaches to the top sites, CHOH and CH O adsorb at the bridge sites, while COH and CHO occupy the three-fold sites. The DFT calculations indicate that the rupture of the initial C–H bond promotes the decomposition of CH OH and CH OH, whereas in the case of CHOH, O–H bond scission is favored over the C–H bond rupture. Thus, the most probable methanol decomposition pathway on the Pd/WC(0001) surface is CH OH → CH OH → -CHOH → CHO → CO. The present study demonstrates that the synergistic effect of WC (as carrier) and Pd (as catalyst) alters the CH OH decomposition pathway and reduces the noble metal utilization.

关键词: density functional theory     methanol     direct methanol fuel cells     WC(0001)-supported Pd monolayer     decomposition mechanism    

Calculation and analysis of sub/supercritical methanol preheating tube for continuous production of biodieselvia supercritical methanol transesterification

Wen CHEN, Weiyong YING, Cunwen WANG, Weiguo WANG, Yuanxin WU, Junfeng ZHANG,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 423-431 doi: 10.1007/s11708-009-0075-0

摘要: Biodiesel is an important renewable energy. Supercritical methanol transesterification for biodiesel has recently been concerned because of its obvious advantages. The tubular reactor is an ideal reactor for continuous preparation of biodiesel via supercritical methanol transesterification. A methanol preheating tube is necessary for the tubular reaction system because the reaction temperature for supercritical methanol transesterification is usually 520―600K. Therefore, in the range of 298―600K, changes of the density, isobaric capacity, viscosity and thermal conductivity of sub/supercritical methanol with temperature are first discussed. Then on the basis of these thermophysical properties, an integration method is adopted for the design of sub/supercritical methanol preheating tube when methanol is preheated from 298K to 600K at 16MPa and the influencing factors on the length of the preheating tube are also studied. The computational results show that the Reynolds number and the local convection heat-transfer coefficient of sub/supercritical methanol flowing in ф6mm×1.5mm preheating tube change drastically with temperature. For the local overall heat transfer coefficient and the average overall heat transfer coefficient , temperature also has an important influence on them when the inlet velocity of methanol is lower than 0.5m/s. But when the inlet velocity of methanol is higher than 0.5m/s, and almost keep invariable with temperature. Additionally, both the outlet temperature and the inlet velocity of methanol are the key affecting factors for the length of the preheating tube, especially when the outlet temperature is over the critical temperature of methanol. At the same time, the increase of tin bath’s temperature can shorten the required length of the preheating tube. At the inlet flow rate of 0.5m/s, the required length of the preheating tube is 2.0m when methanol is preheated from 298K to 590K at 16MPa with keeping the tin bath’s temperature 620K, which is in good agreement with the experimental results.

关键词: sub/supercritical methanol     preheating tube     integration method     biodiesel    

Co-conversion of methanol and

Shumei Wei, Yarong Xu, Zhaoyang Jin, Xuedong Zhu

《化学科学与工程前沿(英文)》 2020年 第14卷 第5期   页码 783-792 doi: 10.1007/s11705-019-1868-2

摘要: The conversion of -hexane and methanol into value-added aromatic compounds is a promising method for their industrially relevant utilization. In this study, intergrown ZSM-5/ZSM-11 crystals were synthesized and their resulting catalytic performance was investigated and compared to those of the isolated ZSM-5 and ZSM-11 zeolites. The physicochemical properties of ZSM-5/ZSM-11 intergrown zeolite were analyzed using X-ray diffraction, N isothermal adsorption-desorption, the temperature-programmed desorption of ammonium, scanning electron microscopy, Fourier transform infrared spectra of adsorbed pyridine, and nuclear magnetic resonance of Al , and compared with those of the ZSM-5 and ZSM-11 zeolites. The catalytic performances of the materials were evaluated during the co-feeding reaction of methanol and -hexane under the fixed bed conditions of 400°C, 0.5 MPa (N ), methanol꞉ -hexane= 7꞉3 (mass ratio), and weight hourly space velocity= 1 h (methanol). Compared to the ZSM-5 and ZSM-11 zeolites, the ZSM-5/ZSM-11 zeolite exhibited the largest specific surface area, a unique crystal structure, moderate acidity, and suitable Brønsted/Lewis acid ratio. The evaluation results showed that ZSM-5/ZSM-11 catalyst exhibited better catalytic reactivity than the ZSM-5 and ZSM-11 catalysts in terms of methanol conversion rate, -hexane conversion rate, and aromatic selectivity. The outstanding catalytic property of the intergrown ZSM-5/ZSM-11 was attributed to the enhanced diffusion associated with its unique crystal structure. The benefit of using zeolite intergrowth in the co-conversion of methanol and alkanes offers a novel route for future catalyst development.

关键词: ZSM-5/ZSM-11     methanol     n-hexane     cofeeding     aromatics    

Design and analysis of dual fuel methanol-power poly-generation

Minghua WANG , Zheng LI , Weidou NI ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 341-347 doi: 10.1007/s11708-009-0023-z

摘要: A dual fuel head poly-generation flowsheet was designed based on coal gas and coke oven gas. To help clearly understand the system performance, a 1.2×10−3.2×10kg methanol and 274―496MW power poly-generation system was simulated by using the commercially available software ASPEN Plus and GT Pro. The technology scheme, the operating parameters, and the efficiency of the system were also analyzed and evaluated, which will be used for building industrial devices.

关键词: dual fuel     methanol-power poly-generation     CO2 and CH4 reforming     splitting ratio    

标题 作者 时间 类型 操作

Kinetic study of the methanol to olefin process on a SAPO-34 catalyst

Mehdi SEDIGHI,Kamyar KEYVANLOO

期刊论文

Acid resistance of methanogenic bacteria in a two-stage anaerobic process treating high concentrationmethanol wastewater

ZHOU Xuefei, REN Nanqi

期刊论文

Simulation analysis of methanol flash distillation circulation process in biodiesel production with supercritical

Zhengjiao TANG, Cunwen WANG, Weiguo WANG, Jia GUO, Yuanxin WU, Jinfang CHEN, Yigang DING

期刊论文

An efficient technique for improving methanol yield using dual CO

Yang Su, Liping Lü, Weifeng Shen, Shun’an Wei

期刊论文

High-precision diffusion measurement of ethane and propane over SAPO-34 zeolites for methanol-to-olefinprocess

Dali Cai, Yu Cui, Zhao Jia, Yao Wang, Fei Wei

期刊论文

Anaerobic treatment of wastewater containing methanol in up-flow anaerobic sludge bed (UASB) reactor

LIN Yishan, HE Yanling, MENG Zhuo, YANG Shucheng

期刊论文

Process synthesis with simultaneous consideration of inherent safety-inherent risk footprint

Andreja Nemet, Jiří J. Klemeš, Zdravko Kravanja

期刊论文

Impacts of methanol fuel on vehicular emissions: A review

期刊论文

Confinement effects in methanol to olefins catalysed by zeolites: A computational review

German Sastre

期刊论文

Hydrogen production from methanol through dielectric barrier discharge

Baowei WANG, Xu ZHANG, Haiying BAI, Yijun Lü, Shuanghui HU

期刊论文

Experimental study on premixed combustion of spherically propagating methanol-air-nitrogen flames

Xiangang WANG, Zhiyuan ZHANG, Zuohua HUANG, Xibin WANG, Haiyan MIAO,

期刊论文

Mechanism of methanol decomposition on the Pd/WC(0001) surface unveiled by first-principles calculations

Jinhua Zhang, Yuanbin She

期刊论文

Calculation and analysis of sub/supercritical methanol preheating tube for continuous production of biodieselvia supercritical methanol transesterification

Wen CHEN, Weiyong YING, Cunwen WANG, Weiguo WANG, Yuanxin WU, Junfeng ZHANG,

期刊论文

Co-conversion of methanol and

Shumei Wei, Yarong Xu, Zhaoyang Jin, Xuedong Zhu

期刊论文

Design and analysis of dual fuel methanol-power poly-generation

Minghua WANG , Zheng LI , Weidou NI ,

期刊论文