钼酸铵与LaHY固相反应机理

采用TG-DSC技术研究了钼酸铵和La HY在空气气氛中的失重行为,考察了钼酸铵与La HY的固相反应机理,用XRD、BET和NH3-TPD对其物相结构、比表面积和表面酸性进行了表征。结果表明,(NH4)6Mo7O24·4H2O分解产生的表相Mo物种借助固相反应以金属-氧簇定位在La HY分子筛体相笼中形成n Mo Ox·La HY单相复合体,引起分子筛的晶胞收缩,晶胞参数a0减小,比表面积下降。制备的n Mo Ox·La HY较相应La HY分子筛的弱酸中心变化较小,中强酸中心增加,强酸中心略有减少,总酸量增加。以质量分数为0.6%的二苯并噻吩/正癸烷溶液为模型反应物,评价了制备的n Mo Ox·La HY催化剂的加氢脱硫性能。负载Mo质量分数为5.0%制得的n Mo Ox·La HY催化剂在反应压力4.0 MPa,反应液时空速20 h-1,H2/原料液体积比500:1的实验条件下,290℃和310℃的二苯并噻吩加氢脱硫转化率达到了56.38%和88.79%,较相应负载Mo质量分数为20.0%制备的Mo O3/Al2O3催化剂分别提高了约12个百分点和28个百分点,表现出了较高的二苯并噻吩加氢脱硫反应活性。     

硫化型NiMo加氢催化剂制备与表征

以四硫代钼酸铵溶液和硝酸镍溶液为浸渍液,根据活性组分Ni和Mo浸渍顺序的不同,采用真空饱和浸渍法制备了MN系列和NM系列 NiMoS/γ-Al₂O₃催化剂。在固定床加氢中试反应装置上研究了NiMoS/γ-Al₂O₃催化剂对二苯并噻吩加氢反应的催化性能,结果表明,NiMoS/γ-Al₂O₃催化剂对二苯并噻吩加氢反应具有良好的活性和选择性。Ni助剂的加入,有利于二苯并噻吩加氢反应的活性和选择性。MN-0.3为最优NiMoS/γ-Al₂O₃催化剂。在空速10 h^-1、反应压力2.0 MPa、氢油体积比300∶1、氢气预处理温度320 ℃和反应温度300 ℃条件下,催化剂对二苯并噻吩加氢反应转化率达83.9%,加氢反应活性较高。     

Co/Si/Mo/Ni/Al2O3催化剂对汽油加氢脱硫性能的影响

为了研究活性组分的负载对催化剂加氢脱硫性能的影响,设计并制备了Co/Si/Mo/Ni/Al₂O₃多元复合催化剂。通过固定床催化剂评价装置对其进行二苯并噻吩加氢脱硫反应活性评价,并利用X射线衍射仪（XRD）、N₂吸附测试仪、X射线光电子能谱仪（XPS）、扫描电子显微镜（SEM）和Mapping等分析测试手段对催化剂进行表征。结果表明,复合催化剂具有优良的加氢脱硫性能,当活性组分负载量为（0.5%Co）/（1.5%Si）/（3.0%Mo）/（10.0%Ni）/Al₂O₃时,其加氢脱硫性能最高可达到96.1%。     

磷添加方式对NiMo/Al2O3催化剂加氢脱硫性能的影响

采用分步浸渍法制备了不同磷添加方式改性的NiMo/Al₂O₃催化剂,在固定床微反装置上考察了该系列催化剂对焦炉煤气中噻吩加氢脱硫（HDS）性能的影响,采用BET、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、NH₃程序升温脱附（NH₃-TPD）、C₄H₄S(H₂)程序升温脱附[C₄H₄S(H₂)-TPD]、X射线光电子能谱（XPS）、高清透射电镜（HRTEM）和拉曼（Raman）等分析手段对催化剂进行表征。结果表明,不同磷添加方式制备NiMo/Al₂O₃催化剂的HDS性能存在较大差异。其中,催化剂PNi-Mo/Al和PMo-Ni/Al表面弱吸附解离活性位增强,对焦炉煤气中噻吩有较好的低温加氢脱硫活性,以含292.5mg/m³噻吩的模拟焦炉煤气为原料时,PNi-Mo/Al在250℃下对噻吩的脱硫率达61%。对于PNi-Mo/Al和PMo-Ni/Al催化剂,先浸渍P、Ni或者P、Mo时,P优先和载体Al₂O₃作用,减弱了活性金属组分Ni、Mo与载体间的相互作用,而又防止Ni或者Mo与载体间相互作用过低而聚集,提高了Ni、Mo在载体表面的均匀分散,生成能够促进硫化形成Ⅱ型活性相Ni-Mo-S的NiMoO₄物种。NiMoO₄和MoO₃之间的协同作用提高了催化剂的硫化度,使HDS活性得以提高。     

TiO2对重整预加氢催化剂性能的影响

采用纳米TiO₂对氧化铝进行改性,并以改性氧化铝为载体制备系列催化剂,通过N₂物理吸附、XRD、H₂-TPR和NH₃-TPD等方法研究TiO₂对催化剂的孔结构、物相和酸性的影响,并考察TiO₂对重整预加氢反应性能的影响。结果表明,添加TiO₂降低催化剂的比表面积和孔容,促进氧化钼的还原,增强催化剂的中强酸,催化剂性能得到较大改善,在入口温度低10 ℃的条件下,催化剂仍具有较好的脱硫和脱氮性能。     

碳基载体石油馏分加氢脱硫催化剂研究进展

总结了以活性炭、碳纳米管、介孔碳、石墨烯等碳基材料为载体的加氢脱硫催化剂的研究进展。与常规Al₂O₃基载体催化剂相比,碳基载体催化剂比表面积大,活性金属的分散性好,活性金属-碳表面间的相互作用弱,有利于形成高活性的Ⅱ类活性相。以二苯并噻吩及4,6-二甲基二苯并噻吩等含硫有机物为处理对象,碳基载体加氢脱硫催化剂总体上具有比Al₂O₃基载体催化剂更高的加氢脱硫催化活性。为满足碳基载体加氢脱硫催化剂的工业应用要求,需要降低制备成本,并针对催化体系的特点进行孔结构优化及表面改性,同时,还需要加强对碳基加氢催化剂加氢脱硫反应机理和动力学方面的研究,以促进催化剂与工艺技术的进步。     

微波热解制备g-Fe2O3催化剂及其SCR脱硝性能

以FeSO₄·7H₂O[Fe(NO₃)₃·9H₂O]为铁源,采用新型微波热解法制备γ-Fe₂O₃[a-Fe₂O₃]催化剂样品,通过XRD、N₂等温吸附-脱附、压汞法等实验手段对催化剂样品晶相、微观孔结构等进行表征;考察两种催化剂样品的NH₃-SCR脱硝性能,通过归一化处理得到两种催化剂在不同温度下的本征脱硝反应速率,同时对比研究了γ-Fe₂O₃与钒系催化剂的脱硝活性;研究氨氮比、氧浓度等运行参数对γ-Fe₂O₃催化剂NH₃-SCR脱硝性能的影响规律,并对其抗硫抗水性能进行考察.结果表明:采用新型微波热解法可得到纯度较高的γ-Fe₂O₃催化剂,其介孔分布合理且大孔数量丰富;同时γ-Fe₂O₃催化剂表现出优于a-Fe₂O₃催化剂的脱硝性能,400℃时最大NO_x转化率达到96%,300、325、350℃下单位面积脱硝速率达到a-Fe₂O₃催化剂的3倍左右;γ-Fe₂O₃催化剂具备优良的抗硫抗水性能,其最佳氨氮比为1、最佳氧体积分数为3.5%.     

甲基咪唑盐酸盐/草酸型低共熔溶剂的制备及其在模拟油中氧化脱硫中的应用

通过简单加热并搅拌甲基咪唑盐酸盐和草酸的混合物合成了甲基咪唑盐酸盐/草酸（[HMIM]Cl/H₂C₂O₄）型酸性低共熔溶剂,以[HMIM]Cl/H₂C₂O₄为萃取剂和催化剂、H₂O₂为氧化剂催化氧化法脱除模拟油中的二苯并噻吩,考察不同的脱硫体系、反应温度、催化剂加入量、氧硫比、模拟油中含硫化合物类型对脱硫率的影响。实验表明,在反应温度为40℃、模拟油量为5 ml、[HMIM]Cl/H₂C₂O₄加入量为1.25 ml、O/S 12、反应时间为140 min的最佳反应条件下二苯并噻吩的脱除率可以达到92.2%。动力学分析表明,该氧化脱硫体系符合一级反应动力学方程。循环使用7次后催化剂的活性没有明显降低。     

程序升温还原法制备MoP催化剂及加氢脱硫性能

采用共沉淀法将钼酸铵和磷酸氢二铵盐的前驱体,通过程序升温还原法(TPR)制备了Mo P加氢脱硫(HDS)催化剂。以质量分数为0.8%的二苯并噻吩/十氢萘溶液为模型化合物,考察了催化剂的HDS反应性能,并用XRD对催化剂晶相进行了表征。实验证明,TPR还原法制备的Mo P催化剂具有较高的加氢脱硫活性。XRD表征结果表明,制备的Mo P催化剂与标准卡片(PDF 24-0771)具有完全吻合的特征衍射峰。     

Ni/Al2O3-SiO2催化剂表面性质及顺酐加氢性能

以Al₂O₃质量分数为10%的Al₂O₃-SiO₂复合氧化物为载体,通过浸渍法制备一系列不同Ni负载量的Ni/Al₂O₃-SiO₂催化剂。运用BET、XRD、H₂-TPR和NH₃-TPD-MS方法研究催化剂表面性质随活性金属Ni负载量的变化规律,探讨催化剂表面性质的变化对其顺酐加氢活性、选择性及催化剂稳定性的影响。结果表明,Ni/Al₂O₃-SiO₂催化剂中的Ni质量分数由5.0%增加至12.5%时,γ-丁内酯收率由7.9%快速增至38.9%,进一步增加Ni质量分数至20.0%,γ-丁内酯收率增加趋于平缓。催化剂中Ni活性物种与催化剂酸性中心的数量是影响催化剂顺酐加氢活性的主要原因。     

Mesoporous molecular sieve MCM-41 supported Co–Mo catalyst for hydrodesulfurization of petroleum resids

In this work, we explored the potential of mesoporous zeolite-supported Co–Mo catalyst for hydrodesulfurization of petroleum resids, atmospheric and vacuum resids at 350–450°C under 6.9 MPa of H₂ pressure. A mesoporous molecular sieve of MCM-41 type was synthesized; which has SiO₂/Al₂O₃ ratio of about 41. MCM-41 supported Co–Mo catalyst was prepared by co-impregnation of Co(NO₃)₂·6H₂O and (NH₄)₆Mo₇O₂₄ followed by calcination and sulfidation. Commercial Al₂O₃ supported Co–Mo (criterion 344TL) and dispersed ammonium tetrathiomolybdate (ATTM) were also tested for comparison purposes. The results indicated that Co–Mo/MCM-41(H) is active for HDS, but is not as good as commercial Co–Mo/Al₂O₃ for desulfurization of petroleum resids. It appears that the pore size of the synthesized MCM-41 (28 Å) is not large enough to convert large-sized molecules such as asphaltene present in the petroleum resids. Removing asphaltene from the resid prior to HDS has been found to improve the catalytic activity of Co–Mo/MCM-41(H). The use of ATTM is not as effective as that of Co–Mo catalysts, but is better for conversions of >540°C fraction as compared to noncatalytic runs at 400–450°C.     

Supported MoO3 catalysts: preparation by the new “slurry impregnation” method and activity in hydrodesulphurization

A new preparation of supported MoO₃ is described. Slurry MoO₃/water is used instead of the solution (NH₄)₆Mo₇O₂₄. Preparation and HDS activity are illustrated for MoO₃ supported over Al₂O₃, active carbon and ZrO₂. Another application of the new principle is the preparation of high surface area MoO₃/MgO by the reaction of MgO with slurry (NH₄)₆Mo₇O₂₄/methanol. Texture of MgO that is deteriorated in aqueous solution of (NH₄)₆Mo₇O₂₄ is stable in that slurry. “Slurry impregnation” is a special case of equilibrium adsorption impregnation. It is simple and it provides monolayer dispersion of molybdena.     

Inhibition effect of H2O on V2O5/AC catalyst for catalytic reduction of NO with NH3 at low temperature

The inhibition effect of H₂O on V₂O₅/AC catalyst for NO reduction with NH₃ is studied at temperatures up to 250 °C through TPD, elemental analyses, temperature-programmed surface reaction (TPSR) and FT-IR analyses. The results show that H₂O does not reduce NO and NH₃ adsorption on V₂O₅/AC catalyst surface, but promotes NH₃ adsorption due to increases in Brønsted acid sites. Many kinds of NH₃ forms present on the catalyst surface, but only NH₄⁺ on Brønsted acid sites and a small portion of NH₃ on Lewis acid sites are reactive with NO at 250 °C or below, and most of the NH₃ on Lewis acid sites does not react with NO, regardless the presence of H₂O in the feed gas. H₂O inhibits the SCR reaction between the NH₃ on the Lewis acid sites and NO, and the inhibition effect increases with increasing H₂O content. The inhibition effect is reversible and H₂O does not poison the V₂O₅/AC catalyst.     

The structure analysis of MoOx/TiO2(110) by polarization-dependent total-reflection fluorescence X-ray absorption fine structure

The surface structure analysis of a model catalyst MoO_x/TiO₂(110) was for the first time performed by polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) in three different directions of the crystal surface. Two samples of MoO_x/TiO₂(110) were prepared by an impregnation of (NH₄)₆Mo₇O₂₄·4H₂O using ultra high purity water and normal distilled water. The PTRF-XAFS analysis revealed that anisotropic Mo dimer species was preferentially formed on the TiO₂(110) surface, with Mo–Mo bond (0.335 nm) parallel to the direction when the ultra high purity water was used as the solvent. On the other hand, the Mo oxide on the surface prepared using normal distilled water had a symmetric tetrahedral structure (MoO₄) with Mo–O of 0.176 nm, which was due to the coexistence of alkaline metals at the surface.     

硫酸锰室温固相球磨制备四氧化三锰

利用软锰矿吸收硫酸镁热解尾气二氧化硫制得硫酸锰,再与碳酸氢铵室温下固相球磨反应,制备出前躯体碳酸锰,经热分解获得四氧化三锰。分别考察了物料比、球磨时间、球料比等因素对硫酸锰转化率的影响,采用XRD对产物进行了分析。结果表明,在n（碳酸氢铵）∶n（硫酸锰）=3.5∶1、球磨时间为40 min、球料质量比为5∶1时,硫酸锰的转化率可达99.8%,将固相产物在1 000 ℃热解1 h后所制备的四氧化三锰纯度为99.9%。该工艺操作简单,产品纯度高,成本低,为硫酸锰制备四氧化三锰提供了新的途径。     

活性炭改性对松香歧化用Pd/C催化剂性能的影响

采用沉积-沉淀法制备了4% Pd/C催化剂（Pd质量分数4%）,分别以硝酸、盐酸、双氧水和氨水4种溶剂对Pd/C的载体活性炭进行改性,并对载体活性炭的比表面积和孔结构、零电荷点（PZC）以及活性组分Pd的分散度进行了表征,研究了活性炭改性对Pd催化剂在松香歧化反应中催化性能的影响。结果表明：经氨水改性后活性炭比表面积孔径增大且活性炭PZC值升高,有利于活性组分Pd在载体表面的分散,以氨水改性活性炭为载体制备得到的Pd/C催化剂活性最高,在催化剂投料量为0.03%,280℃反应2 h条件下,脱氢枞酸质量分数高达81.7%。     

NH3-TPD and XPS studies of Ru/Al2O3 catalyst and HDS activity

The effects of pretreatment of catalyst on its surface properties and the HDS activity of a 0.49% Ru/Al₂O₃ catalyst were studied in a single-pass, differential microreactor. The surface properties of the catalyst were measured by NH₃-TPD and XPS analysis. The Ru/Al₂O₃ catalyst was pretreated in three ways: reduced in H₂ (Ru-R catalyst), oxidized in air and subsequently reduced in H₂ (Ru-OR catalyst), or sulfided in H₂S/H₂ (Ru-S catalyst). Three types of peaks (low, middle, and high temperatures) were observed in the NH₃-TPD study. The predominant high-temperature peak was observed for both the Ru-OR and Ru-S catalyst, pretreated at 300°C. Mass spectrometry showed that the high-temperature peak in NH₃-TPD consisted of N₂ and H₂ formed from the decomposition of NH₃ on the ruthenium sites. NO adsorption of unsaturated Ru species was related to the low-temperature peak in the NH₃-TPD. The XPS analysis showed that the peaks at 279.9 eV, 280.6 eV, and 282.5 eV were ascribed to metallic ruthenium, RuO₂, and RuO₃, respectively. The low-, middle-, and high-temperature peaks were assigned to RuO₂, acid sites on alumina, and metallic Ru, respectively. Metallic ruthenium was effective in the HDS of thiophene and the decomposition of NH₃.     

Water-soluble niobium peroxo complexes as precursors for the preparation of Nb-based oxide catalysts

In the frame of research aimed at developing new synthetic procedures of multimetallic Nb-based catalysts, peroxo complexes of niobium(V) of general formula A^I₃[Nb(O₂)₄] and A^I₃[Nb(O₂)_x(H_yL)]·nH₂O (A^I: NH₄⁺, CN₃H₆⁺ (gu); L: oxalate, tartrate, citrate) have been prepared and characterized on the basis of elemental and thermal analysis, FTIR and ¹³C-NMR spectra. The crystal structure of (gu)₃[Nb(O₂)₄] and (gu)₃[Nb(O₂)₂(C₂O₄)₂]·2H₂O have been determined. The application of the obtained Nb complexes as precursors for the preparation of silica-supported Nb–Mo–O catalysts has been demonstrated. Combining Nb peroxo-carboxylato compounds with analogous Mo(VI) compounds in a silica-impregnation method carried out in aqueous medium leads to the formation of the supported Nb₂Mo₃O₁₄ phase.     

Carbon black composites—supports of HDS catalysts

HDS activity of sulfided Mo (W) catalysts supported on carbon black composites (CBC) is affected by kind of functional groups present on the CBC surface. Oxidation of CBC with (NH₄)₂S₂O₈ produce functionalities with the highest acid strength and corresponding catalyst exhibits the highest HDS activity. Sulfided W/CBC is less active in thiophene HDS than corresponding Mo counterpart. The rate of thiophene HDS over Mo/“basic” CBC does not depend on the method of Mo deposition.