Effect of Calcined Temperature on Coke Deposition for Autothermal Reforming of Methane with Ni-Cu Catalyst

Ni/CuO-ZrO₂-CeO₂-Al₂O₃ catalysts were prepared by co-precipitation method at pH=9 and using Na₂CO₃ as the precipitant. The Ni loading (mass fraction) of the catalysts was 10%. The catalysts were characterized by X-ray diffraction, temperature-programmed oxidation (TPO), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The effects of calcined temperature of support on coke deposition were studied. TPO, SEM and XPS results indicated there was no peak of higher temperature oxygen consumption on Ni/CuO-ZrO₂-CeO₂-Al₂O₃catalyst (support was calcined at 800 ^oC), which could lead to the deactivation of the catalyst. The carbon species were carbonate and inactive carbon (filamentous carbon species) on the surface of catalyst reacting for 40 h which perhaps led to the deactivation of the catalyst.     

多孔介质中甲烷水合物的分解特性

利用定容降压方法测定了在不同多孔介质中甲烷水合物的分解实验数据, 所使用的多孔介质平均孔径分别为9.03, 12.95, 17.96和33.20 nm, 其中孔径为12.95 nm的多孔介质采用了3个粒径范围, 分别为0.105～0.150, 0.150～0.200和0.300～0.450 mm; 其它孔径的多孔介质的粒径范围为0.105～0.150 mm. 在封闭的条件下测定了不同温度与不同初始生成压力下甲烷水合物的分解实验数据(实验温度范围为269.15～278.15 K, 初始生成压力范围为4.1～11.0 MPa), 结果表明, 水合物的分解速度随着初始生成压力的增加和水浴温度的降低而升高, 也随孔径的增加而升高, 但随多孔介质粒径的增大而降低. 在孔径较大和分解温度较低时, 多孔介质中水合物分解引起的温度降低会使水结冰, 从而减缓水合物的分解速度.     

甲烷部分氧化制合成气Ⅰ．催化剂设计

在已有的关于甲烷催化部分氧化和催化氧化资料的基础上，假设了一个甲烷部分氧化反应的机理，并据此提出了催化剂设计的原则．在分析了Ｏ２，ＣＯ和Ｈ２等在金属表面上的吸附热的基础上，得出如下结论：金属Ｎｉ，Ｐｔ，Ｐｄ，Ｒｈ，Ｒｕ和Ｉｒ可作为甲烷部分氧化催化剂的主要组分，Ｃｕ将是最佳助剂，具有较好的氢溢流功能的Ａｌ２Ｏ３可作为最佳载体     

甲烷压缩因子的测定

本文根据Burnett方法,利用已有的实验装置,对温度分别为25℃、50℃,压力达到10MPa的甲烷气体进行了实验研究,得到了相应状态下的甲烷的维里系数和压缩因子;并且对照文献值作了比较。误差分析表明结果良好。     

Kinetics of methane steam reforming on a Ni on alumina-titania catalyst

The kinetics of methane steam reforming on a nickel on alumina-titania catalyst, was studied in the range of 773–873 K. A Hougen-Watson type model gives good agreement with the experimental rates.     

Comparison of reactivity of alkane hydroxylation with intact cells and cell- free extracts ofMethylosinus trichosporium OB3b

Kinetic studies for hydroxylation of a series of alkanes (methane, ethane and propane) with intact cells and cell-free extracts ofMethylosinus trichosporium OB3b were carried out.K _m values for alkane hydroxylation with cell-free extracts were lower than those with intact cells, suggesting that cytoplasm plays an important role in the solubility of alkanes to increase their concentration.     

Aromatic hydroxylation catalyzed by toluene 4-monooxygenase in organic solvent/aqueous buffer mixtures

Toluene 4-monooxygenase is a four-protein component diiron enzyme complex. The enzyme catalyzes the hydroxylation of toluene to give p-cresol with ∼96% regioselectivity. The performance of the enzyme in two-phase reaction systems consisting of toluene, hexane, or perfluorohexane and an aqueous buffer was tested. In each of the cosolvent systems, containing up to 93% (v/v) of solvent, the enzyme was active and exhibited regioselectivity indistinguishable from the aqueous reaction. Using the perfluorohexane/buffer system, a number of polycyclic aromatic hydrocarbons were oxidized that were not readily oxidized in aqueous buffer. An instability of the hydroxylase component and a substantial uncoupling of NADH utilization and product formation were observed in reactions that were continued for longer than ∼3 min. More stable enzyme complexes will be needed for broad applicability of this hydroxylating system in nonaqueous media.     

Performance of a Herriott cell, designed for variable temperatures between 296 and 20 K

We designed, fabricated and tested a multipath Herriott cell (or off-axis spherical mirror interferometer) to achieve low temperature absorption measurements. The cell is fabricated entirely from copper, and the 15 cm radius of curvature copper mirrors have gold coated reflective surfaces. The cell was tested at temperatures between 296 and 20 K with a folded absorption path length of 5.37 m utilizing a lead salt tunable diode laser. Short term temperature stability (1 h) of the Herriott cell is better than 0.005 K under normal operating conditions with a temperature uniformity better than 0.01 K (not measurable). The cell was tested by performing collisional cooling experiments on ¹³C¹⁶O₂ in helium at temperatures between 70 and 20 K and by performing more traditional pressure broadening and shift measurements on molecular infrared absorption lines at temperatures between 300 and about 80 K on ¹³C¹⁶O₂ and methane.     

Temperature dependence of rotational relaxation of methane in the 2ν3 vibrational state by self- and nitrogen-collisions and comparison with line broadening measurements

Depopulation rates of rotational levels in the v₃ = 2 vibrational state of ¹²CH₄ are investigated by a pump-probe technique. Methane molecules are excited into selected rotational levels by tuning the pump laser to 2ν₃ lines. The time evolution in population of the excited level after the pumping pulse is monitored by tuning the probe laser to a (3ν₃ ← 2ν₃) line corresponding to a transition with the excited rotational level as the lower level. Measurements were performed from room temperature down to 100 K in pure CH₄ and in CH₄-N₂ mixtures. The rotational relaxation rate coefficients are given for the J = 1, A₂, J = 1, E, J = 1, F₂ and J = 0, F₂ levels. The results are compared with the available data on line broadening coefficients. The temperature dependence of the data on N₂-broadening is particularly well reproduced by the power law deduced from the results on rotational relaxation.