海泡石-Al２Ｏ３混合载体对铂催化剂环己烷脱氢反应的影响

以三氧化二铝或海泡石(Sepiolite)-三氧化二铝混合物为载体,金属铂为活性组分,采用浸渍法分别制备了Pt／Ａl_２Ｏ_３、Pt／Ｓep-Ａl_２Ｏ_３催化剂,并考察了它们对环己烷脱氢反应的性能、抗硫性能及催化剂活性中心的影响。结果表明,Pt／Ｓep-Ａl_２Ｏ_３催化活性及抗硫性能均高于工业用Pt／Ａl_２Ｏ_３催化剂,同时增大了铂催化剂上的活性中心数及分散度。     

液相氧化环己烷制备环己酮的鼓泡塔新工艺

在连续无搅拌鼓泡塔反应器中,以环烷酸钴为催化剂,研究了空气液相氧化环己烷制备环己酮的氧化过程. 考察了空气流速、环己烷停留时间、催化剂浓度、压力及温度对反应效果的影响. 结果表明,在无搅拌鼓泡塔中,采用空气氧化环己烷制备环己酮的适宜操作条件为：反应温度413~423 K,压力1.2~1.5 MPa;当空气表观气速为2.5~3.5 cm/s、环己烷停留时间为30~40 min时,反应转化率为5%~7%,选择性达到80%~85%.     

二氧化碳-环己烷-正庚烷体系高压汽液平衡数据测定

安装和调试了日本AKICO公司制造的高压汽—液平衡(VLE)装置。其测温误差为±0.05K,测压误差为±5kPa。实测的二氧化碳—正戊烷、二氧化碳—正庚烷VLE数据与文献值具有良好的一致性。用本装置测定了二氧化碳—环己烷在323.2K和343.4K的等温二元VLE数据和二氧化碳—环己烷—正庚烷三元系在343K下的VLE数据。压力达12MPa。     

环己烷气相氧化裂解制低碳烯烃

环己烷气相氧化裂解与传统的热裂解工艺相比,氧气的介入使环烷烃在较低温度下就能开环裂解。在反应温度650℃时,环己烷发生气相氧化裂解反应,环己烷转化率超过70%、烯烃收率为30%左右,而在此条件下环己烷的热裂解反应几乎不发生。在反应温度750℃、n(环己烷)/n(O2)为0 8、停留时间小于0 7s条件下,采用空气代替纯氧进料,环己烷转化率为90%左右,烯烃收率超过48%,CO收率为14%左右,CO2收率仅为1%左右。     

Structure modification of mordenite through isomorphous Ti substitution: Characterization and catalytic properties

The introduction of Ti atoms by means of TiCl₄ treatment and hydrothermal synthesis has been applied to mordenite zeolite with different structures from silicalite. The incorporation of Ti into the mordenite framework is demonstrated by XRD, FTIR,²⁹Si MAS NMR techniques, and tested with catalytic oxidation reactions. Ti-Al-mordenite catalyses the oxidation ofn-hexane, cyclohexane and benzene with hydrogen peroxide under very mild conditions. These reactions can be performed in methanol, acetonitrile and water as solvents. The rate of the reaction is strongly affected by the kind of solvent.     

Study of Mn-based Catalysts for Oxidative Dehydrogenation of Cyclohexane to Cyclohexene

The gas-phase oxidative dehydrogenation (ODH) of cyclohexane to cyclohexene in the presence of molecular oxygen has been studied over various Mn-based catalysts. It is found that LiCl/MnO_x/PC (Portland cement) catalyst exhibits the highest catalytic performance, and a 42.8% cyclohexane conversion, 58.8% cyclohexene selectivity and 25.2% cyclohexene yield can be achieved under 600 °C, 20,000 h⁻¹ and C₆H₁₂/O₂/N₂=14/7/79. There are good correlations between the selectivities to cyclohexene and the electrical conductivities of Li doped Mn-based catalysts, from which it is deduced that the non-fully reduced oxygen species (O₂⁻, O₂²⁻, O⁻) involved in a new phase of LiMn₂O₄ might be responsible for the high selectivity toward cyclohexene, whereas the Mn₂O₃ crystal phase results in the CO_x formation. The selectivity to cyclohexene increases with increasing molar ratio of Li to Mn in LiCl/MnO_x/PC.     

钛硅分子筛在己内酰胺工业中的应用研究进展

综述了钛硅分子筛在己内酰胺工业中应用研究进展 ,阐述了钛硅分子筛的发展和应用将对聚酰胺工业产生的巨大影响。指出今后对钛硅分子筛在己内酰胺工业中应用研究应集中在优化催化剂合成技术和过氧化氢合成技术 ,降低成本等方面。     

Viscosity measurements near a critical point using a novel torsion oscillator

A torsion-oscillator viscometer has been constructed for the measurement of the viscosity of fluids near both liquid-vapor and liquid-liquid critical points. This viscometer has a resolution of ±0.2% and operates at a low frequency (0.6 Hz) and a very low shear rate (0.05 Hz). Thus, it can be used closer to critical points than other viscometers before encountering the non-Newtonian phenomena associated with critical slowing down. This viscometer was used to study the viscosity anomaly near the consolute point of mixtures of methanol and cyclohexane along paths of constant pressure and paths of constant volume at temperatures spanning the range 10^–5 < (T-T _c)/T _c<10^–2. The data are consistent with a simple, power-law divergence of the viscosity with a multiplicative background characterized by an apparent exponent y0.041. Recent theoretical estimates for y are near 0.033. If the data are to be fit with the theoretical value of y, one must simultaneously restrict the range of the data and introduce additional unphysical parameters into the fitting function.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

The Role of the Support in the Oxidative Destruction of Chlorobenzene on Pt/Zeolite Catalysts: An FT-IR Investigation

The vapor-phase cyclohexane oxidative dehydrogenation has been investigated over several catalysts. A typical catalyst for total oxidation, as Mn₂O₃, materials applied in the field of oxide hydrogenation reactions, as silica-supported vanadia- and niobia-based catalysts, V-, Fe-, and Ce-phosphates used for partial oxidation reactions and ZSM5 zeolite, protonic and Co exchanged, have been tested. Over almost all the catalysts, benzene is the main product obtained, although cyclohexene is obtained with high selectivity at low conversion on phosphate catalysts.