HYDROGEN SULFIDE POISONING OF METHANOL SYNTHESIS Cu-BASED CATALYST (II') POISONING OF COMMERCIAL CATALYST

In the absence of H₂S and with the addition of inlet H₂S content 719 ppm for 4 hours, 8 hours and 12 hours respectively, the global reaction rates of methanol decomposition were determined over φ 5×5 mm cylindrical pellet of C207 Cu -based catalyst at atmospheric pressure in an internal recycle gradientless reactor. The pore size distribution, the profile of sulfur in pellet, and the tortuosity factor of the poisoned catalyst were also measured. The hydrogen sulfide poisoning of commercial catalyst was considered as the shell-progressive poisoning. The experimental values of the non-poisoned dimensionless radius x_c by Auger Electron Spectroscopy were 0·938, 0·916 and 0·896 respectively with the addition of H₂S for 4 hours, 8 hours and 12 hours, which were in agreement with the values calculated by the intrinsic deactivation kinetics.     

HYDROGEN SULFIDE POISONING OF METHANOL SYNTHESIS Cu-BASED CATALYST (III) EFFECTIVENESS FACTOR OF POISONED CATALYST

The single component model and the multicomponent model of the effectiveness factor ζ_d, of the poisoned catalyst have been proposed and solved by the orthogonal collocation method. The center equilibrium dead zone was founded in catalyst pellets. The calculated values ζ_d, were respectively 0·1229-0·2907,0·1298-0·2445 and 0·0690-0·2155 for No. 1, No. 2 and No. 3 catalyst. The average of the absolute values of the relative deviations between the experimental values and the calculated values by model for ζ_d was less than 11 per cent. The models can be used to calculate the effectiveness factor of the poisoned catalyst.     

低温浆态合成甲醇催化剂的失活原因

提出了低温液相合成甲醇催化剂失活的主要原因是羰化催化剂甲醇钠的失活。原料中水和二氧化碳对甲醇钠的失活影响小于３％,反应中甲醇脱水的影响也不大。甲醇钠失活的主要原因是反应体系中的甲酸甲酯与甲醇钠发生副反应生成了甲酸钠,该副反应随反应温度的增加而增加,随甲酸甲酯浓度的增大而增大。     

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     

REGENERATION OF LIQUID PHASE METHANOL SYNTHESIS CATALYST

ABSTRACT

This work focuses on the influence of changes in catalyst structure on the catalytic activity in liquid phase methanol synthesis process. Long-term methanol production experiments were performed under various reaction environments in order to investigate the relationship between the catalytic activity and the crystallite size in the methanol synthesis catalyst. The regeneration experiments were also conducted in order to reduce the crystallite size of aged catalysts by inducing metallic phase redispersion. The experimental results showed that the drop in the catalytic activity was closely linked to the growth in the crystallite size in the catalyst. The crystallite size was reduced successfully by cyclic oxidation-reduction treatments and as a result the lost activity in aged catalysts was recovered.     

REGENERATION OF LIQUID PHASE METHANOL SYNTHESIS CATALYST

This work focuses on the influence of changes in catalyst structure on the catalytic activity in liquid phase methanol synthesis process. Long-term methanol production experiments were performed under various reaction environments in order to investigate the relationship between the catalytic activity and the crystallite size in the methanol synthesis catalyst. The regeneration experiments were also conducted in order to reduce the crystallite size of aged catalysts by inducing metallic phase redispersion. The experimental results showed that the drop in the catalytic activity was closely linked to the growth in the crystallite size in the catalyst. The crystallite size was reduced successfully by cyclic oxidation-reduction treatments and as a result the lost activity in aged catalysts was recovered.     

硫对甲醇催化剂C207失活影响的研究

采用电子能谱仪,X光衍射仪,吸附仪等大型物化仪器和化学分析法。对几个厂家生产的C207催化剂在六个厂的工业使用情况进行了研究和剖析,结果表明：硫的存在严重影响催化剂的使用寿命,大量物化数据还表明,硫使催化剂中毒失活的原因是在催化剂表面一定深度内生成了ZnS等物质。     

KINETICS OF METHANOL SYNTHESIS IN THE SLURRY PHASE

The kinetics of methanol synthesis, from synthesis gas, over a commercial Cu-Zn-Al catalyst, in a three phase slurry reactor was studied in a 1 liter, top agitated, baffled autoclave. From the rate data on methanol formation, a Langmuir-Hinshelwood type rate expression has been developed which is sufficient for desing calculations,process improvement, and optimization of operating conditions. The kinetic model developed is free from pore diffusional resistances and is not masked by any mass transfer effects. The results of this kinetic model are in good agreement with the experimental results.     

KINETICS OF METHANOL SYNTHESIS IN THE SLURRY PHASE

ABSTRACT

The kinetics of methanol synthesis, from synthesis gas, over a commercial Cu-Zn-Al catalyst, in a three phase slurry reactor was studied in a 1 liter, top agitated, baffled autoclave. From the rate data on methanol formation, a Langmuir-Hinshelwood type rate expression has been developed which is sufficient for desing calculations,process improvement, and optimization of operating conditions. The kinetic model developed is free from pore diffusional resistances and is not masked by any mass transfer effects. The results of this kinetic model are in good agreement with the experimental results.     

硫化氢对FX—02催化剂烷基化性能的影响

研究了H2S对FX－02催化剂上苯与稀乙稀烷基化反应的影响。认为是H2S占据了催化剂的活性位,妨碍了反应物的吸物和反应。结果表明,在FX－02催化剂上利用干气制乙苯时,应对干气进行脱硫预处理。     

Pt/MOR催化异丙苯临氢脱烷基的失活动力学研究

在固定床积分反应器中实验研究了Pt/MOR催化剂催化重芳烃临氢脱烷基的失活动力学。实验以异丙苯为反应原料,在反应压力0.8 MPa、温度范围673.15~733.15K、体积空速1~2h-1的条件下,得到了失活动力学数据。基于实验现象建立了Pt/MOR催化剂幂函数表观失活动力学模型,即由反应产物引起的连串失活。通过拟合实验数据估计了失活动力学模型的参数。结果表明:外扩散对脱烷基反应的影响可以忽略不计,内扩散对脱烷基反应的影响较小;异丙苯临氢脱烷基的反应活化能和催化剂失活的活化能分别为44.15kJ/mol和79.00kJ/mol。Pt/MOR催化剂失活动力学模型的秩和与残差分布检验结果表明,该失活动力学模型在显著性水平α=0.05下是显著的,即所得失活动力学模型有较高的拟合精确度和可信度。     

甲醇制二甲醚用工业催化剂的失活原因

采用低温氮吸附、热重-差示扫描量热、X射线衍射、红外、扫描电子显微镜等手段,研究了工业上使用的氧化铝系二甲醚催化剂的失活原因。结果表明:在工业使用条件下,二甲醚催化剂床层积炭2.43%~4.46%;部分γ-氧化铝发生再水合反应,生成薄水铝石,晶粒度变大,表面积下降,这些原因共同导致了催化剂活性下降。     

硫氯共存对甲醇催化剂失活的影响

采用电子能谱仪、X光衍射仪、BET吸附仪等大型物化仪器,对硫氯共存时甲醇催化剂中毒失活情况进行研究和剖析,结果表明：硫、氯共存时甲醇催化剂的中毒与只有硫存在时甲醇催化剂的中毒不同,主要表现在几个方面：(1)只有硫存在时,甲醇催化剂硫中毒失活的主要原因是在催化剂外表面一定的径向深度内生成了ZnS,中毒区域在催化床层的上层,具有明显的分层现象;(2)硫氯共存时,硫使甲醇催化剂的中毒仍表现在催化剂外表面的一定深度内生成ZnS,但由于氯中毒的作用,使催化剂产生“低温烧结”现象,烧结后的催化剂抗硫能力大大减小,催化剂的硫容也相应减少,因而硫可能从催化床层的上层向中层或下层移动,导致催化剂硫中毒的分层现象减弱或消失;(3)氯中毒的主要原因是由于在催化剂上生成ZnCl2和CuCl2,ZnCl2和少量CuCl2在催化剂表面流动,并与Cu和Zn0发生置换反应,破坏催化剂的稳定结构,晶粒长大,发生氯中毒的“低温烧结”现象;(4)氯中毒不具有分层现象,同时在催化剂表面的径向分布与硫中毒明显不同。     

负载型金属催化剂上甲醇液相重整制氢研究

研究了Pt,Ru,Ni为活性金属的负载型催化剂上甲醇质量分数为5%的水溶液的液相重整反应。在合适的温度、体积空速下,Pt基催化剂表现出较好的反应性能,甲醇转化率可达99%,H2选择性达98%以上,产物中CO体积分数小于0.01%。Ni/Al2O3催化剂可使甲醇转化率最高达到98%以上,H2选择性随转化率升高而下降,但不低于80%。Ru/Al2O3催化剂上甲醇的转化率最高,可达到98%以上,但其H2选择性随着转化率的升高,从68%快速下降至20%,明显与Pt、Ni基催化剂上的反应机理不同。根据反应条件和产物组成变化,进一步探讨甲醇反应路径,当产物中H2与CH4选择性比值高于2/3时,反应路径以重整制氢为主;当比值低于2/3时,反应路径以甲烷化为主。     

负载型金属催化剂上甲醇液相重整制氢研究

研究了Pt,Ru,Ni为活性金属的负载型催化剂上甲醇质量分数为5%的水溶液的液相重整反应。在合适的温度、体积空速下，Pt基催化剂表现出较好的反应性能，甲醇转化率可达99%，H2选择性达98%以上，产物中CO体积分数小于0.01%。Ni/Al2O3催化剂可使甲醇转化率最高达到98%以上，H2选择性随转化率升高而下降，但不低于80%。Ru/Al2O3催化剂上甲醇的转化率最高，可达到98%以上，但其H2选择性随着转化率的升高，从68%快速下降至20%，明显与Pt、Ni基催化剂上的反应机理不同。根据反应条件和产物组成变化，进一步探讨甲醇反应路径，当产物中H2与CH4选择性比值高于2/3时，反应路径以重整制氢为主；当比值低于2/3时，反应路径以甲烷化为主。     

待生剂上焦炭部分氧化制CO本征反应动力学

制备了碳含量（w）为1.7%的待生剂作为焦炭反应的原料,在反应温度510~780 ℃区间内,开展了以制CO为目的的焦炭部分氧化本征反应动力学研究,获得了不同反应环境下碳转化速率的本征反应动力学参数。实验结果表明：在碳-水体系中,碳、水的反应级数为零级,碳气化反应的活化能和指前因子分别为161.23 kJ/mol和116.2 g/（g?s）;在碳-氧-水体系中,当氧和水过量时,碳的反应级数为一级,氧、水的反应级数为零级,待生剂上碳含量（w）低于0.5%时,在510~665 ℃下碳气化反应的表观活化能和指前因子分别为38.22 kJ/mol和1.37 s-1;在碳-氧-水体系中,当碳和水过量时,氧的反应级数为一级,碳、水的反应级数为零级,碳气化反应的本征活化能和指前因子分别为79.74 kJ/mol和311 712 s-1;在反应温度低于800 ℃时,CO主要由碳和氧反应生成,待生剂上碳与氧反应初始生成CO与CO2的摩尔比λ与温度T的关系为：λ=8.31e-16 736/(RT)。     

新型耐热联醇催化剂的研制

从改善催化剂结构入手 ,采用快速高温共沉淀工艺 ,添加适量第四组分 Ba,制得 JC 1型联醇催化剂 ,其催化活性、热稳定性、使用寿命等性能超过国内现普遍采用的联醇催化剂 C2 0 7型同类样品的水平     

二氧化碳直接加氢合成二甲醚的本征动力学

 在固定床积分反应器中，在反应温度200～260 ℃、反应压力3.0～4.0 MPa、原料气组成n(H2)/n(CO2)=4.0的条件下，研究了Cu-ZnO-SiO2/HZSM-5复合催化剂上CO2直接加氢合成二甲醚的本征动力学。采用Langmuir-Hinshelwood机理和双活性点反应假设模型，建立了CO2直接加氢合成二甲醚的本征动力学模型，并用Powell方法和定步长龙格-库塔-吉尔方法数值积分相结合来估计模型参数。模型检验结果表明，所得的本征动力学模型与实验数据吻合良好。研究结果可为CO2加氢合成二甲醚过程的放大提供理论依据。     

正戊烷和甲醇共芳构化反应中Zn/ZSM-5催化剂的失活研究

对正戊烷和甲醇共芳构化反应与单独芳构化反应进行了比较,通过催化剂连续反应及再生的方法对共芳构化反应中导致Zn/ZSM-5催化剂失活的因素进行了系统的探究,并采用X射线衍射(XRD)、氨气程序升温脱附(NH3-TPD)、吡啶吸附红外光谱(Py-FTIR)、氮气吸附-脱附等方法对新鲜剂和再生后的催化剂进行了表征。结果表明：共芳构化反应相比于甲醇单独芳构化反应,催化剂失活减慢,共芳构化反应相比于正戊烷单独芳构化反应,可以得到更高的芳烃选择性;共芳构化反应中有甲醇存在时,催化剂除了积炭失活外,还存在分子筛水热脱铝失活,导致再生后的催化剂不能完全恢复原有的活性。