An in-situ modified sol-gel process for monolith catalyst preparation used in the partial oxidation of methane

An in-situ modified sol-gel method for the preparation of a Ni-based monolith-supported catalyst is reported. With the presence of a proper amount of plasticizer and binder, and at an optimized pH value, the stable boehmite sol was modified with metal ions (Ni, Li, La) successfully without distinct growth of the particle size. Monolith-supported Ni-based/gamma-Al2O3 catalysts were obtained using the modified sol as the coating medium with several cycles of dip-coating and calcination. Combined BET, SEM-EDS, XRD and H-2-TPR investigations demonstrated that the derived monolith catalysts had a high specific surface area, a relatively homogeneous surface composition, and a high extent of interaction between the active component and the support. These catalysts showed relatively stable catalytic activities for partial oxidation of methane (POM) to syngas under atmospheric pressure. The monolith catalysts prepared by this sol-gel method also demonstrated an improved resistance to sintering and loss of the active component during the reaction process.

STRUCTURE INVESTIGATION OF TI(OBU)4-ALET3 CATALYST BEFORE AND AFTER HEAT-TREATMENT

The catalyst structure of Ti(OBu)4-AlEt3 at different Al/Ti ratios before and after heat aging has been investigated from the data of UV, GC-MS, ESR and C-13 NMR spectra. The complex compounds formed by HTiEt2 and AlEt2(OBu) exist mainly in the catalyst solution, and no -OBu ligands linking with Ti atoms can be found at an Al/Ti ratio of four before heat aging. Many kinds of catalytic species with different size are formed after heat aging the catalyst at 110-degrees-C for 2 h. Dehydrogenation, accompanied by the valence change from Ti3+ to Ti2+, is observed during the aging process of the catalyst.

Selective formation of aromatic amines by selenium-catalyzed reduction of aromatic nitro compounds with CO/H2O under atmospheric pressure

An efficient method for the catalytic reduction of aromatic nitro compounds to the corresponding aromatic amines is reported. In the presence of selenium as a catalyst, the aromatic nitro compounds are quantitively reduced by CO/H2O to form the corresponding amines under atmospheric pressure. The reduction occurs in high selectivity regardless of other reducible functionalities present on the aromatic ring. There exists a phase transfer process of the catalyst selenium in the reaction. (C) 2004 Elsevier B.V. All rights reserved.

拜耳法赤泥放射性特征及应用途径研究

赤泥是氧化铝生产过程中的工业固体废弃物,具有强碱性和高放射性两个特点。目前赤泥的处置方法主要是建设赤泥堆场，供长期堆放，尚没有对其进行大规模利用的成熟技术。 随着铝工业的发展，亟需开发赤泥处置与资源化利用的新工艺技术。本论文运用环境地球化学的理论方法，采用化学分析、选矿分离、放射性测试等技术手段，对贵州铝厂拜耳法赤泥的放射性特征进行了矿物学研究，并利用铁钛着色机理生产赤泥墙体装修材料进行了应用试验研究，指明了赤泥规模化综合利用的途径。 通过研究，得到以下主要结论： 1）初步确定了赤泥放射性元素主要来源于铝土矿原矿，并赋存于原矿残留的锆石和独居石中。 2) 贵州铝厂拜耳法赤泥所含放射性偏高，倘若利用赤泥制作建筑主体材料，需要慎重考虑。 3）探讨了不同选矿方法对赤泥放射性强度的变化情况，重选、磁选、加磁粉磁选所得赤泥组分与赤泥原样放射性相比较，没有显著性差异。采用现有选矿技术，难以达到分离富集赤泥中含放射性组分。 4）利用拜耳法赤泥中富含Fe2O3和TiO2的着色机理，加入一定量的页岩可以制得金红-褐色系列颜色的彩色墙体装修材料。采用现有烧结砖厂一般生产工艺，利用拜耳法赤泥生产烧结制品，是规模化处理赤泥的一条可行途径。 本论文的研究结果指明了赤泥可行的利用途径是用于建材领域，为制定赤泥大规模资源化利用的技术路线提供了一定的理论基础。

Combined single-pass conversion of methane via oxidative coupling and dehydro-aromatization

A single-pass process with the combination of oxidative coupling (OCM) and dehydro-aromatization (MDA) for the direct conversion of methane is carried out. With the assistance of the OCM reaction over the SrO-La2O3/CaO catalyst loaded on top of the catalyst bed, the duration of the dehydro-aromatization reaction catalyzed by a 6Mo/HMCM-49 catalyst shows a significant improvement, and. the initial deactivation rate constant of the overall process revealed about 1.5 x 10(-6) s(-1). Up to 72 h on stream, the yield of aromatics was still maintained at 5.0% with a methane conversion of 9.6%, which is obviously higher than that reported for the conventional MDA process with single catalyst. Upon the TPR results, this wonderful enhancement would be attributed to an in-situ formation of CO2 and H2O through the OCM reaction, which serves as a scavenger for actively removing the coke formed during the MDA reaction via a reverse Boudouard reaction and the water gas reaction as well.