CRYSTAL SIZE GROWTH IN THE LIQUID PHASE METHANOL SYNTHESIS CATALYST

ABSTRACT

The phenomenon of crystal growth in the methanol synthesis catalyst has been studied. Crystallite size distributions in the cuo/ZnO/Al₂O₃ methanol synthesis catalyst have been determined. The effects of temperature, reaction environment and time under reaction conditions have been studied. It is observed that water in the reaction mixture promotes crystal growth.     

A SINGLE-STAGE, LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS III. DUAL CATALYST CRYSTAL GROWTH, DEACTIVATION, AND ACTIVITY CONSERVATION STUDIES

In the liquid phase dimethyl ether (DME) synthesis process, both the methanol synthesis catalyst )composed of CuO, ZnO, and Al₂O₃) and the methanol dehydration catalyst (composed of gamma-alumina) are slurried in the inert oil phase. Various long-term activity checks were conducted on these dual catalysts to characterize the crystal growth and the thermal aging behavior. X-ray powder diffraction, X-ray fluorescence and elemental intensity compositions, and the crystallite size distributions of the aged catalysts were examined. Based on the current investigation, it was established that the crystal growth and the catalyst deactivation problems in the methanol synthesis catalyst are less severe when it is used along with the methanol dehydration catalyst.     

Cu/MgO催化剂中Cu与MgO协同作用对合成气加氢制甲醇性能的影响

新型高效甲醇(CH₃OH)合成铜基催化剂可克服目前商业铜基催化剂反应活性低和反应过程中易失活等缺点,对实现煤炭资源清洁利用目标具有重要意义。通过共沉淀法合成了一系列Cu/MgO催化剂,利用固定床微分反应器系统对催化剂性能进行了评价,并采用X射线衍射(XRD)、程序升温还原(H₂-TPR)、程序升温脱附(H2-TPD和CO-TPD)以及漫反射傅里叶变换红外光谱(DRIFTS)等表征方法分析了催化剂的物理化学性质,研究了Mg含量(物质的量分数)对铜基催化剂表面结构及合成气制甲醇性能的影响。结果表明,MgO不仅可以改变催化剂表面铜物种的分散度和晶粒尺寸,还可调节铜基催化剂的还原性能,Cu与MgO的协同作用提高了铜基催化剂对合成气的吸附和活化速率,从而提高了催化剂的甲醇合成活性;Mg含量为67%时,催化剂表面Cu⁰物种的晶粒尺寸最小为11.5 nm,在催化剂表面分散效果最明显,展现出最佳的甲醇合成性能,合成气制甲醇的转换频率达到5.67×10^-1s^-1。     

硼硅分子筛的合成及催化重质原料重整反应性能

在Na₂O-TEAOH-B₂O₃-SiO₂-H₂O体系中,以水热法合成了硼硅分子筛,考察了合成条件对硼硅分子筛合成的影响,并以所合成的硼硅分子筛为载体制备催化剂,考察其对重质原料重整反应的催化性能。结果表明：模板剂投量及SiO₂/B₂O₃配比对分子筛产物的晶型起关键作用,选择适宜的条件可以合成出高结晶度的硼硅β分子筛。以正十三烷为重质原料模型化合物时,负载Pt的硼硅β分子筛催化剂具有较好的芳构化性能,产物中C₉+芳烃含量较低,BTX（苯、甲苯和二甲苯）和萘的收率明显高于使用PR-D工业重整催化剂时的结果。以Pt/硼硅β分子筛催化剂处理重质原料时,反应压力不宜过低,高温、低空速有利于BTX的生成。     

V_2O_5/TiO_2上甲醇催化合成甲酸甲酯

报道了采用共沉淀法制备的复相催化剂 V2 O5/Ti O2 进行甲醇气固相氧化合成甲酸甲酯的研究结果 ,探讨了催化剂配比、原料配比、反应温度等因素对反应结果的影响 ,并对催化剂进行了 X射线衍射分析测试。结果表明 ,适宜的操作条件为催化剂配比 V/Ti=1 (原子比 )、n(CH3 OH)∶ n(O2 ) =1、反应温度为 1 65℃、空速3 60 0 h-1。该体系催化剂具有较好催化活性和稳定性 ,具有工业化前景     

苯胺、尿素和甲醇催化精馏合成苯氨基甲酸甲酯反应

采用催化精馏装置,以γ-Al₂O₃为催化剂,考察了反应操作条件对苯胺(AN)、尿素和甲醇合成苯氨基甲酸甲酯(MPC)反应的影响,并考察了γ-Al₂O₃催化剂的活性稳定性。结果表明,MPC合成反应的适宜的操作条件为反应温度180℃,反应压力0.80～0.85 MPa,回流比0.50,反应原料分为2股进料,其中,苯胺、尿素和甲醇的混合液以n(AN)∶n(Urea)∶n(Methanol)=1∶5∶75的比例在反应段上方进料,进料速率0.3 mL/min,另一部分纯甲醇在反应段下方进料,进料速率5.0 mL/min。在此条件下,苯胺转化率为99.0%,MPC收率和选择性分别为69.5%和70.2%,γ-Al₂O₃催化剂连续运行408 h后,其催化活性几乎没有变化。     

A SINGLE-STAGE,LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS III. DUAL CATALYST CRYSTAL GROWTH,DEACTIVATION, AND ACTIVITY CONSERVATION STUDIES

ABSTRACT

In the liquid phase dimethyl ether (DME) synthesis process, both the methanol synthesis catalyst )composed of CuO, ZnO, and Al₂O₃) and the methanol dehydration catalyst (composed of gamma-alumina) are slurried in the inert oil phase. Various long-term activity checks were conducted on these dual catalysts to characterize the crystal growth and the thermal aging behavior. X-ray powder diffraction, X-ray fluorescence and elemental intensity compositions, and the crystallite size distributions of the aged catalysts were examined. Based on the current investigation, it was established that the crystal growth and the catalyst deactivation problems in the methanol synthesis catalyst are less severe when it is used along with the methanol dehydration catalyst.     

THERMAL STABILITY ANALYSIS OF THE LIQUID PHASE METHANOL SYNTHESIS REACTOR

The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H₂-rich and CO-rich syngas respectively, were used to experimentally verify the “slope” and “dynamic” critria in a three-phase fixed bed recycle reactor. The liquid medium, witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapor phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics.     

STUDY OF KINETICS OF LIQUID PHASE DIMETHYL ETHER SYNTHESIS FROM SYNTHESIS GAS

The kinetics of liquid phase dimethyl ether synthesis from synthesis gas had been studied when catalyst concentration varied in the range from 10 to 30 grams of dual catalyst in 300 mL of liquid paraffin. DHE productivity and methanol equivalent productivity decreased with increasing catalyst concentration, and as reaction temperature was increased, the two productivities reached their peaks at 280 °C. Unlike above productivities, methanol productivity decreased with both catalyst concentration and reaction temperature. A lump reaction rate expression was developed for the methanol equivalent productivity in terms of CO partial pressure. Both the prequency factors and activation energies are functions of catalyst concentration, increasing with catalyst concentration increasing.     

ROLE OF IN-SITU PRODUCED METHANOL ON THE CATALYST DEACTIVATION IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

The role of methanol produced in-situ in the liquid phase methanol synthesis process has been experimentally examined. The catalyst crystallite size is found to be more stable when the produced water and methanol are consistently removed from the catalyst active sites. The experimental evidence shows that in-situ produced water is not the only culprit for the catalyst crystallite size growth, rather, methanol is also responsible for contributing to crystallite growth and therefore catalyst deactivation

Hydrothermal leaching of the catalyst was also determined to be an active participant in catalyst deactivation. Two experimental designs were run to assess the influence of temperature, leaching solution concentration and pretreatment conditions on the extent of leaching of the methanol synthesis catalyst. Water and methanol were found to be active participants in the reduction of catalyst activity. Hence, the methanol/water solutions serve as potentially harmful agents in the leaching of aluminum and copper from the synthesis catalyst     

ROLE OF IN-SITU PRODUCED METHANOL ON THE CATALYST DEACTIVATION IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT

The role of methanol produced in-situ in the liquid phase methanol synthesis process has been experimentally examined. The catalyst crystallite size is found to be more stable when the produced water and methanol are consistently removed from the catalyst active sites. The experimental evidence shows that in-situ produced water is not the only culprit for the catalyst crystallite size growth, rather, methanol is also responsible for contributing to crystallite growth and therefore catalyst deactivation

Hydrothermal leaching of the catalyst was also determined to be an active participant in catalyst deactivation. Two experimental designs were run to assess the influence of temperature, leaching solution concentration and pretreatment conditions on the extent of leaching of the methanol synthesis catalyst. Water and methanol were found to be active participants in the reduction of catalyst activity. Hence, the methanol/water solutions serve as potentially harmful agents in the leaching of aluminum and copper from the synthesis catalyst     

羰化-氢解法低温合成甲醇 Ⅴ.催化反应宏观动力学研究

采用磁传动搅拌反应器 ,对使用自制的铜铬氧化物甲醇合成催化剂的低压宏观反应动力学特性进行了实验研究。采用幂律法对实验数据进行处理 ,建立了催化剂的宏观反应动力学方程。在 35 3～ 393K温度范围内 ,催化反应的活化能为 6 7 0kJ/mol,这一数值与甲醇羰化制甲酸甲酯的活化能相近     

Methanol to lower olefins conversion in a slurry reactor: Effects of acidity and crystal size of silicoaluminophosphate catalysts

Effects of the crystal size and acidity of silicoaluminophosphates on their catalytic behavior in the methanol to lower olefins conversion in a slurry reactor have been studied. It has been found that an increase in the crystal size of silicoaluminophosphate causes a reduction in its catalytic activity, which is due to an increase in diffusion limitations for both reagents and reaction products. An increase in the number of acid sites and their localization on the outer catalyst layer improve the time stability of silicoaluminophosphate performance and the selectivity of methanol conversion to lower olefins.     

稀土畦体超强酸催化合成苯乙酸甲酯

本文以稀土固体超强酸SO4^2-/TiO2/La^3 为催化剂,苯乙酸和甲醇为原料合成了苯乙酸甲酯,考察了影响反应的因素。结果表明,醇酸比为3：1,催化剂用量为10g/mol苯乙酸,反应时间为3h为最佳反应条件,酯化率为89．1％。     

IN-SITU ACTIVATION OF METHANOL SYNTHESIS CATALYST IN A THREE-PHASE SLURRY REACTOR

In the liquid phase methanol synthesis process, syngas reacts in the presence.of fine catalyst particles slurried in the oil phase, in a three phase slurry reactor system. A method for activating high concentration ( ≤25 wt. %) of the CuO-ZnO-Al₂O₃ catalyst in the catalyst-oil slurry has been successfully developed. This catalyst activation process can be of crucial significance in the research and development of the methanol synthesis process in a liquid entrained reactor.

The reducing gas contains 2% hydrogen in nitrogen mixture and this activation procedure is carried out at a pressure of 125 psi. The catalyst-oil slurry is subjected to a controlled temperature ramping from 110° to 250° C. The catalyst has beemshown to be effectively reduced after following this activation procedure, that is valid especially for high catalyst loadings in slurry. Since the reduction is carried out in the process liquid medium and inside the reactor system, the catalyst-oil slurry after the treatment is ready for the synthesis of methanol.     

POST-REDUCTION TREATMENT OF LIQUID PHASE METHANOL SYNTHESIS CATALYST USING CARBON DIOXIDE

This work focuses on the investigation of the catalyst post-treatment in the liquid phase methanol synthesis process. The novel post-treatment process, using carbon dioxide, has been developed and experimentally proven to be effective not only in maintaining the initial catalytic activity over a long period of usage but also in improving the mechanical and chemical strength of the catalyst. It was also found that the role of ZnO in the catalytic reaction, if any, can be nicely replaced by ZnCO₃.     

THE ROLES OF CARBON DIOXIDE IN METHANOL SYNTHESIS

The roles played by carbon dioxide in the chemistry of methanol synthesis over CuO/ZnO/A1₂O₃ catalysts have been experimentally investigated. It was concluded based on reaction rate measurements and thermodynamic considerations, that the two reactions that best describe the chemical system of methanol synthesis are the CO₂-hydrogenation and water-gas shift reactions. It was also found experimentally that the presence of CO₂ is vital for maintaining the catalytic activity. The significance of the study is enhanced by the fact that this was the first such investigation of the global chemistry of methanol synthesis to be based on the novel liquid phase process. It was also observed that the rates of methanol synthesis attained a maximum when the concentration of carbon dioxide in the reactor feed was controlled at a certain optimal value. The optimal CO₂ content was found to be a function of the operating temperature and syngas composition. The experimental data are especially important because the apparatus and the operating conditions have been well-defined and carefully chosen to closely simulate industrial reactors.     

La_2O_3对合成异丁醛催化剂V_2O_5的催化性能的影响

研究了La2O3对甲醇乙醇一步催化合成异丁醛催化剂V2O5的催化性能的影响。实验结果表明,La2O3的添加量(质量分数)为10%时La2O3/V2O5活性最佳,在反应温度375℃,常压,体积空速2h-1,原料甲乙醇的摩尔比为3∶1时,乙醇转化率达96.62%,异丁醛选择性达61.76%。对反应前后的催化剂进行的XRD测试结果表明,反应过程中V2O5还原为V2O3,部分La2O3也发生了晶形的变化,由立方体晶体(A型)变为了六方体形晶体(C型)。对V2O5和La2O3/V2O5反应后失活催化剂进行的TG-DTA实验结果表明,La2O3可降低失活催化剂的再生温度,有利于失活催化剂的再生。     

Synthesis of lower olefins from dimethyl ether in the presence of zeolite catalysts modified with rhodium compounds

The catalytic properties of zeolite catalysts modified with rhodium compounds in the synthesis of olefins from dimethyl ether (DME) and methanol (MeOH) have been studied. The optimum concentration of rhodium in the composition of a zeolite catalyst has been determined. It has been shown that one of the possible precursors of ethylene in the conversion of DME is ethanol, which, under reaction conditions, can be formed through both the DME isomerization and methanol homologation stages.     

一步法合成二甲醚反应中水煤气变换反应的初步研究

在反应温度为260℃、压力5.0MPa的条件下,研究了固定床反应器中不同CO空速和CO/H2O比例在甲醇合成催化剂上进行水煤气变换反应的情况,并对催化剂的稳定性进行了考察。研究结果发现,CO空速升高和CO/H2O比例减小都能抑制副反应的发生,Cu基催化剂水煤气变换功能减弱速率快是导致二甲醚复合催化剂失活快的主要原因。