Effect of hydrometallurgical process parameters on the Mn2O3 nano catalysts derived from spent batteries used in the plasma catalytic oxidation of BTX

Manganese oxide catalysts have been synthesized from the used batteries via hydrometallurgical method and effect of hydrometallurgical parameters such as the effect of acid type (H₂SO₄, HNO₃, HCl), acid concentration (0.5, 1, 1.5, 2 %v/v) and powder to acid ratio (1/50, 1/60, 1/70, 1/80) were in detail investigated. The physico-chemical properties of as-prepared catalysts were characterized by FT-IR, XRD, FESEM, EDX, BET, TEM, and TPR-H₂ analysis. The activity of as-prepared catalysts were investigated towards the oxidation of benzene, toluene, and xylene (BTX) in a plasma-catalytic process. The results show that benzene and toluene conversion were almost constant in the range of 97–98% in case of various acid types, acid concentrations and solid to liquid ratios. However, the xylene conversion were varied in case of different hydrometallurgical factors. The highest xylene conversion was obtained in the presence of MnS0.5–60, which was prepared using H₂SO₄ with concentration of 0.5%v/v and solid to liquid ratio of 1/60. The effect of the input voltage and BTX flow rate on the BTX conversion was also investigated using MnS0.5–60 catalyst in detail.     

Analysis of microbial adaptation at enzyme level for enhancing biodegradation rate of BTX

Catechol was found to be a common intermediate in the degradation of benzene and toluene byAlcaligenes xyhsoxidans Y234, and the ring cleavage of the catechol mediated by catechol 1,2-dioxygenase was a rate-determining step. Since benzene induced higher level of catechol 1,2-dioxygenase than toluene, the cells pre-adapted to benzene showed higher degradation rate of benzene and toluene. The degradation rate ofm-xylene was also increased significantly when benzene-adapted cells were inoculated.m-Xylene was metabolized via 3-methyl catechol which was effectively cleaved by catechol 1,2-dioxygenase.     

Bench-scale and field-scale evaluation of catechol 2,3-dioxygenase specific primers for monitoring BTX bioremediation

The objective of this work was to test a molecular genetic method for in situ monitoring of aerobic benzene, toluene, and xylene (BTX) biodegrading microorganisms. Catechol 2,3-dioxygenase (C23DO) genes occur in bacteria that biodegrade benzene, toluene, xylenes, phenol, biphenyl, and naphthalene. A competitive quantitative polymerase chain reaction (QC-PCR) technique using a single set of primers specific for an entire subfamily of C23DO genes was recently developed. To determine whether bacteria containing these C23DO genes actually exist in environments contaminated by BTX, aerobic microcosms containing previously uncontaminated soil were amended with different aromatic hydrocarbons and DNA extracts were analyzed by QC-PCR for C23DO genes. Anaerobic microcosms were established to confirm that oxygen was also necessary for the enrichment of C23DO genes. Field testing was done at two sites undergoing monitored natural attenuation. In microcosm experiments naphthalene, m-xylene, and p-xylene strongly enriched for C23DO genes while benzene, toluene, and o-xylene produced only transient, weakly detectable genes. In the field study, C23DO genes were detected in groundwater samples contaminated with either xylenes or naphthalene. The results of this study demonstrated that molecular genetic techniques can provide an accurate and rapid method to detect microorganisms capable of aromatic hydrocarbon biodegradation. Such a technique would be useful for monitoring the effectiveness of aeration technologies and for documenting microbial processes for monitored natural attenuation.     

离子液体支撑液膜用于分离混合芳烃的研究

利用不同离子液体制备离子液体"充填型"支撑液膜,将其用于混合芳烃中对二甲苯的蒸汽渗透膜分离实验,比较了不同离子液体、不同支撑底膜、原料中对二甲苯的含量、操作温度等因素对分离性能的影响。结果表明,在40℃温度下,[Bmim][BF4]填充PVDF膜形成的支撑液膜对对二甲苯体积分数为60%的混合芳烃渗透通量为59.5 g/(m2·h),分离因子达16.5;经过90 h的实验测定,支撑液膜分离性能稳定。离子液体支撑液膜的蒸汽渗透过程能够实现从混合芳烃中将对二甲苯分离。     

Product distribution and catalytic performance of nano-sized H-ZSM-5 zeolites in the methanol-to-aromatics (MTA) reaction

A study of the effect of SiO₂/Al₂O₃ molar ratio on the activity and selectivity of H-ZSM-5 catalyst in the reaction of methanol to aromatics (MTA) has been carried out in this work. Aluminosilicate zeolite (ZSM-5) zeolites with different SiO₂/Al₂O₃ molar ratios were successfully synthesized by the hydrothermal method. The SiO₂/Al₂O₃ molar ratio of the prepared ZSM-5 zeolite particles could be easily controlled by changing the ratio of tetraethylorthosilicate to aluminum nitrate nonahydrate. The effect of SiO₂/Al₂O₃ molar ratio on the activity of nano-sized H-ZSM-5 zeolites in the MTA reaction was studied. The H-ZSM-5 zeolite catalyst with low SiO₂/Al₂O₃ molar ratios shows remarkable selectivity toward aromatics and benzene, toluene, and xylene (BTX) in the MTA reaction.     

DMCplus控制器在三苯精馏单元的应用

Aspen Tech的DMCplus先进过程控制软件在中国石油兰州石化公司重整一芳烃联合装置的三苯精馏单元得到了成功应用。不仅提高了装置运行平稳率和馏出口合格率，而且在提高三苯收率，降低运行费用方面也取得了成效。     

Carbon-based monoliths for the catalytic elimination of benzene, toluene and m-xylene

The catalytic behaviour of Pt supported on carbon-based monoliths was studied in the low-temperature catalytic combustion of benzene, toluene and m-xylene and compared with the corresponding behaviour of Pt supported on γ-Al₂O₃ coated monoliths. Carbon-based monoliths showed a much better catalytic performance which is ascribed to the fact that the carbon surface is more hydrophobic than the γ-Al₂O₃ one, and the release of water molecules produced during the combustion is favoured.     

临氢裂解及烷基化组合技术应用于C9混合芳烃的高值化

随着国内八大炼化基地的逐步建成与投产,未来C₉混合芳烃的产量将大幅上涨,如何高效利用C₉混合芳烃将成为大型炼厂需要重点解决的问题。本文以重整装置副产的C₉混合芳烃为原料,经临氢裂解、临氢烷基化组合技术,生产高价值的苯/甲苯/二甲苯（BTX）和均四甲苯,反应条件缓和,目的产物选择性高。在最佳反应条件下,油相产物平均收率为86.94%,其中富含BTX的C₅~C₉馏分平均含量为80.93%,均四甲苯平均含量为12.98%,C₁₀⁺馏分（不含均四甲苯）平均含量为6.09%。对于C₉混合芳烃年处理量为9万吨的工业装置,通过本文提供的组合技术可实现年利润5543.5万元。本文提出的C₉混合芳烃的组合技术具有较高的技术可行性和经济可行性,符合炼化一体化的发展趋势,是未来炼厂解决C₉混合芳烃出路的首选途径之一。     

菲加氢裂化制BTX的催化反应研究

采用性能较优的6%Ni/USY催化剂,进行菲加氢裂化制取苯、甲苯、二甲苯(BTX)的反应研究。探讨了不同反应压强、反应温度及进料速率对反应的影响,实验结果表明:反应压强4 MPa、反应温度420℃、进料速率<0.27 mL/min时,转化率可达95%左右,且BTX的选择性约60%,并结合反应机理对实验结果进行了探讨。