利用合成SAPO-34分子筛的晶化残液合成SAPO-34分子筛

在制备SAPO-34过程中会产生大量的晶化残液,晶化残液中除了含有大量水之外,还含有残留的模板剂(有机胺)、硅源、铝源、磷源等组分,通过向合成SAPO-34分子筛产生的晶化残液中加入适量的铝源、磷源、硅源、模板剂等物料制备成凝胶混合物,经过老化、水热晶化、洗涤、干燥和焙烧等工序,即得到纯净的SAPO-34分子筛,既保护了环境又实现了晶化残液的再利用。     

苯胺催化加氢制环己胺的技术概况

介绍了苯胺催化加氢制环己胺的技术概况,对各工艺的优缺点进行了评述,并叙述了苯胺催化加氢制环己胺催化剂的发展情况。     

Assessment of the catalytic effect of various biomass ashes on CO2 gasification of tire char

The aim of this study was to determine the effect of various biomass ashes, comprising catalytically active components, on tire char reactivity during the CO₂ gasification process. Ashes from the combustion of corn cobs, beet pulp, sunflower husks and beech chips were selected for the research. Moreover, industrial fly ash from a coal-fired power plant was used as a reference. The tire char-ash blends with different ash contents (0–15 wt%) were gasified in the CO₂ atmosphere under non-isothermal conditions using dynTHERM Rubotherm thermobalance. Based on the n-order Coats and Redfern method, gasification reactivity indicators and kinetics parameters were calculated. The results showed that the addition of biomass ashes enhanced reactivity of tire char, and the magnitude of these changes depended on both the quantity and type of the additive. With the increase in the amount of added biomass ashes, the catalytic effect increased, and their efficiency can be ranked as follows: sunflower husk ash > corn cobs ash ≅ beet pulp ash > beech chips ash. In turn, reference fly ash from a power plant slightly affected the CO₂ gasification of tire char, regardless of its amount. Moreover, a statistically significant correlation between the reactivity indicator and the amount of K₂O, MgO and P₂O₅ in ashes analysed has been proved (reactivity indicator improved with an increase in these components amount). The performed analysis provides valuable information regarding the composition of catalysts characterised by high catalytic activity in the tire char gasification process.     

Enhancing gas phase Fischer-Tropsch synthesis catalyst design

This paper presents the results on the research in the development of a Fe-based catalyst with Co as a co-catalyst, and Ru and ZnO as promoters. The catalytic performance of these materials for FT synthesis was investigated in the gas phase employing a fixed bed reactor system. The Fe-Zn-K/γ-Al₂O₃ catalyst performance was used as the benchmark. The data show that by varying the process conditions (T, P, flow rate), it is possible to achieve a narrow distribution of the liquid products. The effect of co-catalysts and promoters such as K and Zn are also presented. The results from a series of Fe₄Co₁Zn_0.04 based catalysts for Fischer-Tropsch (FT) synthesis, in which the different amounts of Ru are incorporated showed that the addition of Ru suppressed the CH₄ formation at the cost of increasing the CO₂ selectivity. The newly designed catalysts showed significantly high activity towards CO conversion (>70%), along with low selectivity towards CO₂ (5-15%) and methane (ND - 3%). It is also shown that the support material plays a role in the selectivities obtained.     

XANES investigation of the enhanced chemical stability of Pd in supported Pd–Mo catalysts

The XANES (X-ray absorption near edge structure) technique was used to study Pd and Mo catalysts deposited on supported Al₂O₃/SiO₂ and Al₂O₃/Si-MCM-41 in the form of monometallic and bimetallic systems. The results indicate that Pd has stronger chemical stability when in the presence of Mo and is always in the metallic form, which is surprising, because the samples were not subjected to reducing conditions prior to the measurements. The increased stability was attributed to the formation of a core-shell structure with a Pd rich core and a Mo rich surface.     

Carbon-supported tetragonal MnOOH catalysts for oxygen reduction reaction in alkaline media

Carbon-supported MnOOH catalyst was prepared by reducing KMnO₄ with carbon Black Pearls 2000. TEM and XRD characterization results show that nanosized tetragonal MnOOH crystals formed in the specimen when the MnOOH content ranged from 9 wt.% to 36 wt.%. The oxygen reduction reaction (ORR) activity of the catalyst with different amounts of MnOOH content in alkaline media was investigated using a rotating disc electrode (RDE) and a rotating ring-disc electrode (RRDE). The number of electrons involved in the ORR increased from 3.2 to 3.9 with the increase of the MnOOH content from 9 wt.% to 36 wt.% in the catalyst. The kinetic current increased to 0.0184 A cm⁻² when the MnOOH content was increased to 72 wt.%. However, both the number of electrons and the kinetic current decreased when the MnOOH content was increased from 72 wt.% to 90 wt.%. The MnOOH/C catalyst with optimized MnOOH content and suitable loading in the cathode is promising for applications in alkaline fuel cells.     

C1化学工业中的贵金属催化剂

叙述了贵金属催化剂在C     

Surface Properties and Catalytic Performance of La0.8K0.2CuxMn1–xO3 for Simultaneous Removal of NOx and Soot

The influence of copper substitution in La_0.8K_0.2Cu_xMn_1–xO₃ on its catalytic performance for simultaneous removal of NO_x and soot under oxygen rich conditions was investigated. A series of catalysts was prepared and then characterized by XRD, SEM, BET, and XPS. The temperature programmed reaction (TPR) method was used to evaluate the catalytic performance of the catalysts. XRD results show that the partial substitution of Cu for Mn promotes the formation of perfect perovskites. SEM and BET results demonstrate that appropriate copper substitution enhances the porosity and increases the specific surface area, leading to conditions which are favorable for heterogeneous catalysis. XPS results indicate that a fraction of the Mn³⁺ is converted to Mn⁴⁺ on the addition of low levels of Cu. By correlation of the physicochemical properties and the catalytic performance, a large specific surface area, high porosity, high content of Mn³⁺ and synergistic effects of Mn³⁺ and Cu²⁺ are seen to favor the simultaneous catalytic removal of NO_x and soot.     

Quantitative determination of the number of surface active sites and the turnover frequency for methanol oxidation over bulk metal vanadates

The present work investigates the number and nature of the surface active sites, selectivity and turnover frequency towards methanol selective oxidation of a series of bulk metal vanadates. The catalysts were synthesized through an organic route and characterized by laser Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and specific surface area analysis (BET). The number of surface active sites (N_s) was determined by measuring the concentration of surface methoxy species adsorbed on the catalysts exposed to an atmosphere of 2000 ppm of methanol in helium at 100 °C. The specific activity values (TOFs) were calculated by normalizing the methanol oxidation reaction rate by the number of surface active sites probed by methanol chemisorption. The comparison of the methanol oxidation products distribution from bulk metal vanadates, pure V₂O₅ and corresponding metal oxides (NiO, MnO, etc.) strongly suggests that the metal vanadate catalysts consist of only surface vanadium oxide sites. The comparison of the TOF values demonstrated that bulk metal vanadates possess similar activity to monolayer vanadium oxide supported catalysts and are more active than bulk metal molybdates for methanol selective oxidation. Moreover, bulk metal vanadates are as active and selective as the commercial MoO₃/Fe₂(MoO₄)₃ catalysts at high methanol conversion.