Hydrotreating of gas oil on SBA-15 supported NiMo catalysts

The siliceous and the metal substituted (B or Al)-SBA-15 molecular sieves were used as a support for NiMo hydrotreating catalysts (12 wt.% Mo and 2.4 wt.% Ni). The supports were characterized by X-ray diffraction (XRD), scanning electron microscopy and N₂ adsorption–desorption isotherms. The SBA-15 supported NiMo catalysts in oxide state were characterized by BET surface area analysis and XRD. The sulfided NiMo/SBA-15 catalysts were examined by DRIFT of CO adsorption and TPD of NH₃. The HDN and HDS activities with bitumen derived light gas oil at industrial conditions showed that Al substituted SBA-15 (Al-SBA-15) is the best among the supports studied for NiMo catalyst. A series of NiMo catalysts containing 7–22 wt.% Mo with Ni/Mo weight ratio of 0.2 was prepared using Al-SBA-15 support and characterized by BET surface area analysis, XRD and temperature programmed reduction and DRIFT spectroscopy of adsorbed CO. The DRIFT spectra of adsorbed CO showed the presence of both unpromoted and Ni promoted MoS₂ sites in all the catalysts, and maximum “NiMoS” sites concentration with 17 wt.% of Mo loading. The HDN and HDS activities of NiMo/Al-SBA-15 catalysts were studied using light gas oil at temperature, pressure and WHSV of 370 °C, 1300 psig and 4.5 h⁻¹, respectively. The NiMo/Al-SBA-15 catalyst with 17 wt.% Mo and 3.4 wt.% of Ni is found to be the best catalyst. The HDN and HDS activities of this catalyst are comparable with the conventional Al₂O₃ supported NiMo catalyst in real feed at industrial conditions.     

介孔分子筛SBA-15在催化领域的应用进展

从负载固体酸催化剂、金属和金属氧化物以及手性催化剂三方面综述了介孔分子筛SBA-15在催化领域应用的研究进展;并展望了介孔分子筛SBA-15在催化领域的研究方向。     

Synthesis and characterization of Co-containing SBA-15 catalysts

Two Co-SBA-15 catalysts were synthesized and characterized by thermogravimetry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, porosity, UV–visible diffuse reflectance and temperature programmed reduction with H₂. The first catalyst was prepared synthesizing SBA-15 and then adding Co ions by impregnation (Co_imprSBA-15). The second catalyst was prepared using a more complex procedure of immobilization of cobalt ions in the presence of pyridine and H₂O₂ on –COOH groups anchored to the SBA-15 structure [Co-SBA-15(COOH)]. These COOH groups were created starting from cyano groups introduced during the synthesis of the periodic mesoporous materials as 4-triethoxysilylbutyronitrile. Characterization of the samples indicates that in both cases the typical 2D periodical hexagonal structure of SBA-15 was obtained, but with less ordered packing in the second case. The cobalt is highly dispersed in the SBA-15 (up to 9% w/w) and is present mainly as Co²⁺ ions in highly distorted tetrahedral or square pyramidal coordination. Some coordinatively unsaturated Co(II) Lewis acid centers are present in Co_imprSBA-15, while in Co-SBA-15(COOH) coordination of pyridine to cobalt tentatively may induce the formation of Co³⁺ ions, although in both catalysts the dominant species are Co²⁺ ions in a very close environment.     

CoMo/Ti-SBA-15 catalysts for dibenzothiophene desulfurization

With a view to reducing the sulfur content in diesel fuels, novel desulfurization CoMo catalysts were supported on a Ti-loaded hexagonal mesoporous SBA-15 material. The Ti-SBA-15 substrates were synthesized using triblock copolymers as structure-directing agents. Catalytic activity was assessed in the model reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT), carried out in a batch reactor at T = 623 K and with a total hydrogen pressure of 3.1 MPa. The reaction proceeds via the direct desulfurization route (main route) and the hydrogenation (HYD) pathway. The incorporation of Ti into the SBA-15 afforded catalysts that were more active than the Ti-free counterpart, due to the enhancement of the DDS route in this reaction. This difference was explained in terms of a larger number of coordinately unsaturated sites (CUS) of the metal sulfide on Ti-loaded catalysts. Under steady-state conditions, the CoMoST20 catalyst with a Si/Ti ratio of 20 was the most active among the catalysts studied. Since this catalyst exhibited both Ti⁴⁺ ions incorporated into the SBA-15 framework and separate anatase TiO₂ clusters located on its surface, the activity enhancement on this sample was explained by the larger intrinsic activity of the “Co–Mo–S” phase located on these TiO₂ nanoparticles. The Ti-SBA-15 supports and the CoMo/Ti-SBA-15 catalysts were studied by N₂ adsorption–desorption isotherms, XRD, TEM, FTIR of adsorbed pyridine and NO, UV–vis DRS, TPR, micro-Raman and XPS spectroscopy.     

Synthesis and catalytic activity of SBA-15 supported catalysts for styrene oxidation

Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.     

Studies on physico-chemical characterization and catalysis on high surface area titania supported molybdenum hydrotreating catalysts

A series of titania supported molybdenum catalysts were prepared by incipient wetness impregnation method and characterized by BET surface area, XRD, TPR, FTIR, ESCA, and low temperature oxygen chemisorption. Thiophene, cyclohexene and tetrahydrofuran were taken as model compounds for evaluating catalytic activities for hydrodesulfurization (HDS), hydrogenation (HYD), and hydrodeoxygenation (HDO) reactions, respectively. XRD results indicate that molybdenum oxide species are dispersed as a monolayer on the support up to 8 wt.% Mo and the formation of crystalline MoO₃ is observed above this loading. FTIR and TPR results showed that molybdenum oxide species were present predominantly in tetrahedral form at lower loading and polymeric octahedral forms are dominant at higher loading. Both oxygen chemisorption and rates of reaction were found to increase with increasing Mo loading up to 8 wt.% and then decrease with further increase in loading. HDS and HYD activities are more or less same but HDO activity is two times higher than HDS and HYD activities. The results are also interpreted with the help of other parameters, like dispersion, equivalent molybdenum surface area, surface coverage, crystalline size, quasi-turnover frequencies and intrinsic activities. ESCA results suggest that electron transfer is taking place from support to metal.     

Overview of support effects in hydrotreating catalysts

The commercial hydrotreating catalysts are usually composed of a sulfide active phase supported on alumina. It has been known for more than 15 years that other supports might lead to enhanced catalytic properties. The present article summarizes the progress which have been made in this area, often related to new methods of preparation of supports, active phases deposition or activation procedures. The properties of active phases supported on oxides, pure or mixed, basic and acidic supports, zeolites, mesoporous materials, carbon and clays are examined.     

SBA-15固载磷钨酸催化剂的制备及催化合成叔丁基苯酚

以不同硅烷偶联剂改性的介孔分子筛SBA-15为载体、PW_(12)为催化剂,通过对SBA-15表面共价及非共价修饰制备磷钨酸@介孔分子筛/硅烷偶联剂复合催化剂PW_(12)@SBA-15/YSiX_3(YSiX_3=Apts、Atapts、Papts);并利用FT-IR、XRD、TEM、N_2吸附-脱附对其组成、结构及形貌进行表征。以改性SBA-15分子筛固载磷钨酸催化剂催化合成叔丁基苯酚为研究对象,考察不同硅烷偶联剂、反应温度、苯酚与叔丁醇物质的量比对催化合成叔丁基苯酚的影响,并获得合成叔丁基苯酚的最佳工艺条件,即反应温度145℃、n(苯酚)∶n(叔丁醇)=1∶2.5、重时空速2.2 h~(-1),该最佳反应条件下,PW_(12)@SBA-15/Apts催化剂催化合成叔丁基苯酚的催化活性最高,苯酚转化率为98.3%,2,4-二叔丁基苯酚选择性为57.3%.     

Preparation, characterization, and catalytic properties of the Mo2C/SBA-15 catalysts

A series of Mo₂C/SBA-15 catalysts with different Mo contents were prepared by temperature-programmed carburization (TPC). The materials obtained and their oxide precursors (MoO₃/SBA-15) were characterized by Nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) spectroscopy. The activities of the catalysts for deep hydrodesulfurization (HDS) of thiophene were evaluated. The results of N₂ adsorption-desorption isotherms indicated that the surface area and pore diameter of the oxide precursors increase after carburization. The XRD patterns show that Mo₂C particles are highly dispersed in the SBA-15 ordered mesoporous. The test results show that Mo₂C/SBA-15 catalysts have an excellent performance for the deep HDS under the lower temperature region.     

改性SBA-15催化剂用于棕榈酸甲酯脱氧提质

以水热稳定性高的Al-SBA-15介孔分子筛为载体,负载CuO制备了CuO/Al-SBA-15催化剂,并采用一步合成法制备出Fe-Al-SBA-15催化剂,对其进行了XRD、TEM及FTIR测试及表征。分别以Al-SBA-15、CuO/Al-SBA-15及Fe-Al-SBA-15为催化剂,进行了棕榈酸甲酯的非加氢脱氧反应。结果表明:CuO在介孔材料表面均匀分散,3种催化剂中CuO/Al-SBA-15的脱氧效果最好,确定最佳反应条件为反应温度342℃,反应时间2 h。与未加催化剂相比,在最佳反应条件下,棕榈酸甲酯脱羧产生烃类的选择性提高了40%~60%。催化剂重复使用3次,棕榈酸甲酯的转化率无明显下降。根据活性评价推测脱羧反应机理为:在亚临界水中棕榈酸甲酯水解生成棕榈酸,在催化剂的活性中心上羧酸根负离子形成羧基化物,之后被活化氢进攻邻近羧基的C—C键,进而CO2脱附下来,生成主产物十五烷。     

改性SBA-15催化剂用于棕榈酸甲酯脱氧提质

以水热稳定性高的Al-SBA-15介孔分子筛为载体,负载CuO制备了CuO/Al-SBA-15催化剂,并采用一步合成法制备出Fe-Al-SBA-15催化剂,对其进行了XRD、TEM及FTIR等测试及表征。以Al-SBA-15、CuO/Al-SBA-15及Fe-Al-SBA-15为催化剂,进行棕榈酸甲酯的非临氢脱氧反应。结果表明：CuO在介孔材料表面均匀分散,三种催化剂中CuO/Al-SBA-15的脱氧效果最好,确定最佳反应条件为反应温度342 ℃,反应时间2 h。与未加催化剂相比,在最佳反应条件下,棕榈酸甲酯脱羧产生烃类的选择性提高了40~60 %。催化剂重复使用3次,棕榈酸甲酯的转化率无明显下降。根据活性评价推测脱羧反应机理为：在亚临界水中棕榈酸甲酯水解生成棕榈酸,在催化剂的活性中心上羧酸根负离子形成羧基化物,之后被活化氢进攻临近羧基的C-C键,进而CO2脱附下来,生成主产物十五烷。     

SBA-15改性固体酸催化合成乙酸正丁酯的研究

以SBA-15为载体利用尿素水解法制备Zro2/SO2(4)-改性的固体酸SZ/SBA-15,通过XRD、N2吸附-脱附、IR、SEM 、Hammett指示剂法和N H3-TPD法对合成材料的孔结构、骨架结构及表面酸性等进行了表征.实验结果表明,所合成的固体酸催化剂具有典型的介孔结构特征,酸强度在0.80 < Ho <...     

Pt-Sn/SBA-15催化剂的制备、表征和长链烷烃脱氢催化性能

A series of the Pt-Sn/SBA-15 catalysts were prepared and their properties characterized by using X-ray powder diffraction （XRD）, N2 adsorption-desorption, high resolution transmission electron microscope, X-ray photoelectron spectroscopy （XPS） and H2-temperature programmed reduction. Their performances in long chain alkane dehydrogenation were evaluated in a fixed-bed microreactor with dodecane as a model alkane. The results indicated that SBA-15 maintained the well-order mesoporous structure during the reaction. The performance of the catalyst was found not dominated by its textural properties, but by the molar ratio of Sn to Pt which governed the degree of Sn reduction. Owing to the highest degree of Sn reduction, 1% （by mass） Pt-1.8% （by mass） Sn/SBA-15 showed the best catalytic activity. At 0.1 MPa and 470℃, the molar ratio of hydrogen to alkane at 4, and liquid hourly space velocity （LHSV） 20 h^-1, the dodecane conversion is 10%, and the dodecene selectivity is about 70%.     

KOH／SBA-15负载型固体碱催化剂的合成、表征及催化性能

采用后合成法制备出固体碱催化剂KOH／SBA-15,利用X射线衍射法（XRD）、N2吸附-脱附（BET）、透射电镜（TEM）、化学吸附剂表面碱性测定（COz—TPD）等对其进行表征。考察了其在大豆油酯交换反应制备生物柴油中的催化性能。结果表明,在相同反应条件下,与CaO／SBA-15和MgO／SBA-15相比,KOH／SBA-15在催化活性和孔扩散上都具有较大的优越性,催化制备生物柴油产率最高（83．56％）。     

Dendritic SBA-15 supported Wilkinson's catalyst for hydroformylation of styrene

After PAMAM (polyamidoamine) dendrimers have been successfully grown in SBA-15 mesoporous materials, Wilkinson's catalyst (RhCl(PPh₃)₃) precursor has been tethered on these dendritic supports to produce heterogeneous catalysts for hydroformylation reaction of styrene. SBA-15 has been functionalized by two methods. In the passivation method, the silanols outside the SBA-15 pores have been passivated to preclude the rhodium precursor to be tethered outside the channels. The rhodium catalysts supported in the pore channels of this passivated SBA-15 show positive dendritic effects in enhancing the catalytic activity, regio-selectivity and stability of the catalyst by minimizing the leaching of the rhodium complex catalyst from the catalyst support to the liquid-phase media.     

SBA-15 supports modified by Ti and Zr grafting for NiMo hydrodesulfurization catalysts

A series of Ti- and Zr-containing mesoporous SBA-15 supports and their respective NiMo catalysts were prepared to study the effect of the Ti and Zr loading into the support on the characteristics of Ni and Mo surface species and their catalytic activity in the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS). Ti and Zr-containing SBA-15 solids with different metal loading (up to 19 wt.% of TiO₂ or 22 wt.% of ZrO₂) were prepared by chemical grafting. The solids prepared were characterized by N₂ physisorption, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), temperature-programmed reduction (TPR), chemical analysis and HRTEM. The results show that Ti- and Zr-SBA-15 supports with highly dispersed Ti and Zr species can be obtained without substantial loss of SBA-15 characteristics. Zr grafted species showed somewhat better dispersion on the SBA-15 surface than the corresponding Ti counterparts. It was found that TiO₂ and, especially, ZrO₂ incorporation in the SBA-15 support leads to stronger interaction of Mo and Ni species with the support providing better dispersion to the oxidic and sulfided metal species (XRD, TPR, HRTEM). NiMo catalysts supported on Ti- and Zr-containing SBA-15 showed high activity in 4,6-dimethyldibenzothiophene HDS. It can be concluded therefore that SBA-15 materials grafted with Ti or Zr species show promising features as supports for Mo-based hydrotreating catalysts.     

Co-Mo／SBA-15柴油加氢脱硫研究

以介孔分子筛SBA-15为载体,担载Co—Mo双金属活性组分制备了深度加氢脱硫催化剂。通过XRD和BET表征表明,负载金属后SBA-15分子筛仍然保持二维晶相结构,表面积略有下降。以直馏柴油为原料,在固定床反应器上评价了催化剂的脱硫反应活性的结果表明,SBA-15介孔分子筛Co—Mo的负载量为W（CoO）=5％,w（MoO3）=25％;脱硫适宜的反应条件为：反应温度360℃,压力4．0MPa,氢油体积比400．0,空速2．0h^-1。在此条件下,柴油硫含量可由1350μg／g降至39μg／g。     

P/SBA-15催化合成十六烷基苯

采用负载磷酸的SBA-15分子筛作为催化剂,以苯和十六碳烯为原料,经烷基化反应合成十六烷基苯。在微型液相固定床反应器上考察了反应温度、空速、体系压力、磷酸负载量以及苯烯摩尔比等反应条件对催化剂性能的影响。研究结果表明,磷酸的适宜负载量约为7%(质量分数),适宜反应条件为反应温度180℃、空速为2.0 h-1、体系压力为2.0 MPa和苯、烯摩尔比为10。在此条件下,十六碳烯的转化率可达到94.5%,十六烷基苯选择性可达93%。催化剂单程寿命达到120 h以上。负载磷酸的SBA-15催化剂呈现较好的催化活性和稳定性。     

Catalytic combustion of benzene over metal oxides supported on SBA-15

The catalytic combustion of benzene over metal oxides supported on SBA-15 was investigated. The catalysts were prepared by the incipient wetness method and characterized by XRD, BET, TEM, ESR and TPR. The calcined siliceous SBA-15 and CuO/SBA-15 samples displayed well-resolved patterns with a sharp peak at about 1.0°. It is clear that the loading of CuO on the silica matrix drastically decreases the surface area and pore volume of the catalysts, as would be expected for the incorporation of CuO. Among the supported metal oxides, CuO supported on SBA-15 was found to have the highest activity for benzene oxidation. In addition, copper oxide supported on SBA-15 gives higher catalytic activity than copper oxide supported on MCM-41. From the ESR results, the CuO dispersed on the SBA-15 acts as the active site of the CuO/SBA-15 catalysts in the oxidative decomposition of benzene. The catalytic activity gradually increases with increasing CuO loading on SBA-15.