Preparation,characterization and hydrodesulfurization performances of Co-Ni2P/SBA-15 catalysts

A series of Co-Ni2P/SBA-15 catalysts with various Co contents, Ni2P contents and P/Ni molar ratios were prepared by impregnating nickel nitrate, diammonium hydrogen phosphate, and then cobalt nitrate into SBA-15 support followed by temperature-programmed reduction in a H2 flow. The catalyst structure was characterized by X-ray diffraction(XRD), high resolution-transmission electron microscopy(HR-TEM)and N2adsorption-desorption techniques and their catalytic performance of the hydrodesulfurization(HDS) of dibenzothiophene(DBT) was evaluated. The effects of Co contents, Ni2 P contents and P/Ni molar ratios on the catalyst structure and HDS of DBT over the Co-Ni2P/SBA-15 catalyst were investigated. The results indicated that the mesoporous structure was mainly maintained and the nickel phosphides were well dispersed in all of the characterized catalysts. The 4Co-25Ni2P/SBA-15(P/Ni = 0.8) catalyst with the Co and Ni2 P contents of 4 wt% and25 wt%, respectively, and the P/Ni molar ratio of 0.8 showed the highest catalytic performance for HDS of DBT. Under the reaction conditions of 380?C and 3.0 MPa, the DBT conversion can reach 99.62%. The HDS of DBT proceeded mainly via the direct desulfurization(DDS)pathway with biphenyl(BP) as the dominant product on all of the catalysts and the BP selectivity was slightly enhanced after the introduction of Co promoters.     

Mo-Ni2P/SBA-15催化剂的制备、表征及加氢脱硫催化性能

以介孔分子筛SBA-15 为载体, 通过分步浸渍硝酸镍、磷酸氢二铵、钼酸铵, 然后在H₂气流下程序升温还原(H₂-TPR), 制备了一系列不同Mo 含量的Mo-Ni₂P/SBA-15 催化剂. 采用X 射线衍射(XRD)、氮气吸脱附(BET)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)对催化剂的结构进行了表征, 评价了催化剂对二苯并噻吩(DBT)的加氢脱硫(HDS)活性. 结果表明, Mo-Ni₂P/SBA-15 催化剂仍然保留有介孔结构, 催化剂的物相主要是Ni₂P. 催化剂表面的Ni 以Ni^δ+和Ni²⁺形式存在; P以P^δ-和P⁵⁺形式存在; Mo以Mo^δ+和Mo⁶⁺形式存在. Mo能促进催化性能的提高, 其中Mo含量为1% (w, 质量分数)的Mo-Ni₂P/SBA-15 催化剂具有最好的二苯并噻吩加氢脱硫催化活性, 在反应温度为380 ℃, 反应压力为3.0 MPa的条件下, 二苯并噻吩的转化率可达99.03%, 所有考察的Mo-Ni₂P/SBA-15都以直接加氢脱硫(DDS)途径为主.     

Zr改性Ni2P/SBA-15催化剂的制备及其加氢脱氧性能

以正丙醇锆（n）和Zr（SO₄）₂（m）为锆源制备了Zr改性的Ni₂P/ZrO₂-SBA-15（n）和Ni₂P/ZrO₂-SBA-15（m）催化剂,并采用XRD、BET、CO吸附、XPS、NH₃程序升温脱附等手段对催化剂进行了表征。以苯并呋喃（BF）为模型化合物,研究了催化剂加氢脱氧（HDO）性能。结果表明,Zr改性后,形成了新的层状结构的ZrP;Zr的引入有助于生成更多、更小粒径的Ni₂P活性相,催化剂的酸强度和酸量均提高。与正丙醇锆相比,Zr（SO₄）₂为锆源能够获得比表面积大、酸性强、酸量大的催化剂,得到更多的ZrP相、更小粒径的Ni₂P晶粒,暴露更多的Ni活性位点。Ni₂P/ZrO₂-SBA-15（n）和Ni₂P/ZrO₂-SBA-15（m）的BF HDO产率分别为71.5%和85.9%,较Ni₂P/SBA-15分别提高了14.0%和28.4%。催化剂HDO活性、脱氧产物选择性和产率大小顺序为：Ni₂P/ZrO₂-SBA-15（m） > Ni₂P/ZrO₂-SBA-15（n） > Ni₂P/SBA-15。     

Mesoporous SBA-15-supported chiral catalysts: preparation,characterization and asymmetric catalysis

Two mesoporous silica-supported chiral Rh and Ru catalysts 5 and 6 with ordered two-dimensional hexagonal mesostructures were prepared by directly postgrafting organometallic complexes RhCl[(R)-MonoPhos(CH₂)₃Si(OMe)₃][(R,R)-DPEN] and RuCl₂[(R)-MonoPhos(CH₂)₃Si(OMe)₃][(R,R)-DPEN] (DPEN = 1,2-diphenylethylenediamine) on SBA-15. During the asymmetric hydrogenation of various aromatic ketones under 40 atm H₂, both catalysts exhibited high catalytic activities (more than 97% conversions) and moderate enantioselectivities (33–54% ee). Furthermore, the chiral Rh catalyst 5 could be easily recovered and used repetitively five times without significantly affecting its catalytic activity and enantioselectivity. A catalytic comparison of the mesoporous silica-supported chiral Rh catalyst 4 prepared by a postmodification method is also discussed.     

PtZn-Sn/SBA-15合成、表征及对丙烷催化脱氢性能

以SBA-15为载体,利用浸渍法制备了单、双和三金属Pt催化剂,并对催化剂进行了N2物理吸附(BET)、程序升温还原(H2-TPR)、H2-化学吸附、透射电子显微镜(TEM)和O2-脉冲等技术表征,研究了它们对丙烷催化脱氢(CDH)制丙烯反应的催化性能。研究结果表明,Pt在三金属催化剂中的分散性能最好,并且部分负载组分可以进入SBA-15的孔道,Pt的分散度达到29%,Pt粒子尺寸为3 nm左右。三金属催化剂表现出优越的脱氢性能,这主要归结于载体的弱酸性、活性组分和助剂、载体之间的相互作用及Zn对Pt的电子调控作用。这些因素使催化剂的积炭量较低,因而具有较高的脱氢稳定性和极高的选择性。     

Preparation,characterization, and luminescence of (SBA-15) immobilized pepsin

SBA-15 mesoporous silica was synthesized by hydrothermal method and its surface was methylated by treatment with methyltrimethoxysilane. Pepsin was immobilized on the obtained materials giving host-guest composite materials (SBA-15)-pepsin and (methylated SBA-15)-pepsin. The optimum conditions for preparation of these materials were established. Methylated SBA-15 (M-SBA-15) has improved immobilization efficiency of enzyme compared to initial SBA-15 silica. It was shown that with the gradual increase of NaCl solution ionic strength the immobilized amount of enzyme was reduced. Powder X-ray diffraction and Fourier transform infrared spectroscopy showed that the host frameworks in the prepared host-guest composite materials are intact and the ordered structure was retained. Scanning electron microscopic studies revealed fibrous morphologic characteristics of the SBA-15 and the immobilized pepsin composite materials. The average particle diameter of (SBA-15)-pepsin composite was 338 ± 10 and 343 ± 10 nm for (M-SBA-15)-pepsin. The low temperature N₂ adsorption-desorption study at 77 K showed that the pore sizes and specific surface areas of the host-guest composite materials were smaller than those before the introduction of the enzyme, suggesting that the immobilized enzyme occupied a definite position in the host material pore channels. The UV-vis solid diffuse reflectance and luminescence studies showed that the enzyme was successfully immobilized on to the host material and that after the immobilization of enzyme on SBA-15 the conformation of pepsin macromolecule has not been changed.     

柠檬酸络合法制备Ni2P/SBA-15催化剂及加氢脱硫性能

以介孔分子筛SBA-15为载体,Ni组分采用柠檬酸(CA)配合法,制备了Ni2P质量含量为25%～45%、P/Ni为0.8、CA/Ni为0～1.5的一系列CA-Ni2P/SBA-15催化剂.利用XRD和N2吸脱附表征了催化剂结构,以二苯并噻吩(DBT)为模型硫合物,对催化剂加氢脱硫(HDS)性能进行了评价,考察了CA/Ni比对催化剂结构和反应性能的影响.结果表明,催化剂仍然保持有介孔结构,催化活性物相为Ni2P.反应温度为300～340℃时,Ni2P含量和CA/Ni比都对催化剂的性能有一定的影响,反应温度在360℃以上时,Ni2P含量和CA/Ni比对催化剂性能的影响不明显.Ni2P含量为35%、CA/Ni比为1.0的催化剂具有最好的HDS活性,DBT的转化率可达98%.     

Ni2P/SBA-15催化剂的结构及加氢脱硫性能

以硝酸镍为镍源,磷酸氢二铵为磷源,介孔分子筛SBA-15为载体,用共浸渍法制备了含磷化镍前驱体的样品,然后在氢气流中采用程序升温还原法,制备了Ni2P质量分数为5%-40%的Ni2P/SBA-15催化剂.用X射线衍射(XRD)、N2吸附脱附、透射电子显微镜(TEM)、傅立叶变换红外光谱(FTIR)等分析测试技术对催化剂的结构进行了表征,以噻吩和二苯并噻吩(DBT)为模型化合物,在微型同定床反应器上对催化剂的加氧脱硫(HDS)性能进行了评价.结果表明,Ni2P/SBA-15催化剂中SBA-15的介孔结构依然存在,活性组分Ni2P具有良好的分散性,但随Ni2P含量的增加,催化剂的比表面积、孔容和孔径均有明显减小.当反应温度为320℃时,Ni2P含量为15%-25%(w)的催化剂就具有很好的加氢脱硫催化性能;反应温度在360℃以上时,所有催化剂都具有优异的深度脱硫催化性能.Ni2P/SBA-15催化剂对二苯并噻吩的加氢脱硫(HDS)主要以直接脱硫机理(DDS)进行.     

Silylated Co/SBA-15 catalysts for Fischer-Tropsch synthesis

A series of silylated Co/SBA-15 catalysts were prepared via the reaction of surface Si-OH of SBA-15 with hexamethyldisilazane (HMDS) under anhydrous, vapor-phase conditions, and then characterized by FT-IR, N₂ physisorption, TG, XRD, and TPR-MS. The results showed that organic modification led to a silylated SBA-15 surface composed of stable hydrophobic Si-(CH₃)₃ species even after calcinations and H₂ reduction at 673 K. Furthermore, the hydrophobic surface strongly influenced both metal dispersion and reducibility. Compared with non-silylated Co/SBA, Co/S-SBA (impregnation after silylation) showed a high activity, due to the better cobalt reducibility on the hydrophobic support. However, S-Co/SBA (silylation after impregnation) had the lowest FT activity among all the catalysts, due to the lower cobalt reducibility along with the steric hindrance of grafted -Si(CH₃)₃ for the re-adsorption of α-olefins.     

Iron-modified mesoporous SBA-15 silica: Preparation and characterization studies

Fe-SBA-15 materials with different Si/Fe ratios (Si/Fe = 100, 60, 15) have been synthesized by hydrothermal method and characterized by several spectroscopic techniques. Electron spin resonance and Mössbauer spectroscopy, along with electron microscopy and X-ray diffraction, allowed differentiation of several iron species. These species correspond to hematite particles, very small “isolated” or oligomeric Fe^III species possibly incorporated in the mesoporous silica wall, and Fe^III oxide clusters either isolated or agglomerated, forming “rafts” at the surface of the silica and exhibiting ferromagnetic ordering. Because of their agglomeration, these clusters appear with a two-peak size distribution, with one peak corresponding to the isolated clusters formed in the mesopores and still embedded in them and the other corresponding to the agglomerates spread on the surface of the mesoporous silica particles.     

Synthesis and characterization of SBA-3, SBA-15, and SBA-1 nanostructured catalytic materials

A highly ordered large pore mesoporous silica molecular sieve SBA-3, SBA-15, Al-SBA-15, and SBA-1, were developed and characterized by XRD, BET, FTIR, SEM, and NMR-MAS. The catalytic materials were synthesized using different raw materials and operation conditions. These materials contain a regular arrangement of uniform channels with diameters between 1.8 and 10 nm, high specific surface area and high specific pore volume. The designed methods were effective for the synthesis, presenting each mesostructured materials, patterns of XRD and other characteristics corresponding to the reported ones in literature. The new route employed to synthesize Al-SBA-15, generates a catalyst with only aluminum in tetrahedral form, according to the data of (27)Al NMR-MAS. However, several reports indicated that the coordination of the Al atoms changes below the Si/Al ratio of 45, presenting peaks corresponding to penta and hexa-coordinated aluminum, which are absent in our samples (Si/Al = 50 and 33).     

Synthesis and characterization of P4VP/SBA-15 composite by in situ polymerization

Abstract  

Poly(4-vinylpyridine)/SBA-15 (P4VP/SBA-15) composites with various amounts of SBA-15 were prepared and characterized. The physical and chemical properties of P4VP/SBA-15 were investigated by XRD, BET, FT-IR, TGA, and SEM techniques. The catalytic performance of each material was determined for the Knoevenagel condensation reaction between carbonyl compounds and ethyl cyanoacetate in the presence of water as a solvent. The effects of reaction temperature, the amount of catalyst, amount of support, solvent, and the amount of benzoyl peroxide during the synthesis of P4VP/SBA-15 were investigated, as well as the recyclability of the heterogeneous composite. The catalyst used for this synthetically useful transformation showed a considerable level of reusability as well as very good activity. This reaction occurred rapidly when water was used as a solvent, so we assume it to be a green reaction.     

Preparation and characterization of (SBA-15)-La2O3 host-guest composite materials

Lanthanum oxide was successfully incorporated into an SBA-15 mesoporous molecular sieve via the microwave-assisted synthesis method (MASM) for the first time, and was compared with liquid-phase grafting and thermal diffusion methods. A series of characterizations were used to characterize the prepared materials. The results showed that the preparation of (SBA-15)-La₂O₃ host-guest composite materials by MASM has the advantages of simpler operation, higher efficiency and more plentiful lanthanum oxide could be incorporated into SBA-15 compared with other methods. In the prepared host-guest (SBA-15)-La₂O₃ materials, the frameworks of the host molecular sieve were kept intact, their structures were still kept high ordered and the guest lanthanum oxide locates inside the pores of the SBA-15. The sizes of the prepared (SBA-15)-La₂O₃ samples were 340-357 nm. The prepared host-guest composite materials show the properties of luminescence, and the luminescent intensities are about 2 times of bulk La₂O₃.     

Al-Ni2P/SBA-15催化剂的制备、表征及加氢脱硫催化性能

以磷酸氢二铵为磷源,硝酸镍为镍源,硝酸铝为助剂铝源,制备了n_P/n_Ni=0.8,Al含量为1.06wt%~6.35wt%的一系列Al-Ni₂P/SBA-15催化剂。采用XRD、TEM和N₂吸脱附等技术对催化剂的结构进行了表征研究,以二苯并噻吩(DBT)作为模型化合物,在微型固定床反应器上对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,Al修饰的Al-Ni₂P/SBA-15催化剂仍然保持介孔结构,当Al含量低于5.29wt%时,催化剂的物相主要是Ni₂P,当Al含量在5.29wt%-6.35wt%之间时,催化剂的物相为Ni₂P和Ni₁₂P₅。Al含量为4.24wt%的3-Al-Ni₂P/SBA-15催化剂具有最好的二苯并噻吩加氢脱硫催化活性,在反应温度为360 ℃,反应压力为3.0 MP的条件下,3-Al-Ni₂P/SBA-15催化剂对二苯并噻吩的转化率可达99.0%。     

Preparation, characterization and catalytic activity towards green reactions of sulfonic functionalized SBA-15

Acidic heterogeneous catalysts based on the anchorage of sulfonic groups on SBA-15 mesoporous silica were synthesized. In a first synthesis step, samples containing mercapto groups were prepared by co-condensation of tetraethylorthosilicate with 3-mercaptopropyltrimethoxysilane, in presence of ethylene-propylene block copolymer as mesoporous silica structure director. In other samples, mercapto groups were introduced by post-functionalization of the traditional calcined SBA-15. In a second step, these mercapto groups were oxidized in order to get sulfonic acid groups on the surface. Characterization of the samples was carried out by N₂ adsorption-desorption, FTIR, XPS and acid-base titration. Spectroscopic techniques showed that the effective incorporation of sulfonic groups depends on the synthesis methodology used. In turn, the SBA-15 post-synthesis functionalization produces changes in structural characteristics like a decrease in BET surface and changes in the pore size distribution. The as-prepared materials were tested as acid catalysts in the alkylation of isobutane with 1-butene, and in the esterification of free fatty acids with methanol. The results obtained show a lack of activity in the alkylation reaction which can be associated with the formation and stabilization of the intermediate carbocation species.     

Synthesis, characterization and hydrodesulfurization activity of silica-dispersed NiMoW trimetallic catalysts

Silica-dispersed NiMoW trimetallic hydrodesulfurization catalysts were prepared by deposition-precipitation method. For comparative purposes, bulk NiMoW trimetallic catalysts were obtained by co-precipitation. Silica was employed to disperse active metals for full utilization of active components and silica-dispersed NiMoW catalyst had high active metal content. BET analysis showed that silica-dispersed NiMoW trimetallic catalysts had a high surface area (165.1 m²/g) and pore volume (0.27 ml/g). Transmission electron microscopy results proved that active components were well dispersed. Hydrodesulfurization activity of silica-dispersed NiMoW catalysts was much higher than that of comparative catalysts and up to twice greater than those of commercial NiMo alumina-supported systems per gram of catalyst.     

Toluene abatement on Ag-CeO2/SBA-15 catalysts: synergistic effect of silver and ceria

As a typical volatile organic compound, toluene is a hazardous material for human health and the environment, and currently, the development of catalysts for its oxidation into CO₂ and water is crucial. The series of Ag-CeO₂/SBA-15 catalysts is synthesized by wetness impregnation techniques and characterized by a number of physical-chemical methods (nitrogen [N₂] physisorption, small angle X-ray scattering [SAXS], transmission electron microscopy [TEM], and temperature-programmed reduction [TPR]). The toluene sorption and catalytic properties in toluene oxidation are studied. Small silver [Ag] and cerium oxide [ceria, CeO_2] particles with sizes below 3 nm are predominantly formed in the ordered structure of Santa Barbara Amorphous-15 [SBA-15]. The interactions between the Ag and CeO₂ nanoparticles are established. Temperature-programmed desorption of toluene [TPD-C₇H₈] analysis shows that physical adsorption of toluene occurs on pristine SBA-15 material, while the introduction of either silver or ceria to SBA-15 leads to the appearance of additional strongly bound chemisorbed toluene on such sites. When both Ag and CeO₂ are introduced, only chemisorbed toluene is formed over the Ag-CeO₂/SBA-15 catalyst, and the highest catalytic activity in toluene oxidation is observed over this catalyst (T_98% = 233 °C, 0.2% C₆H₅CH₃) that is attributed to the synergistic effect of ceria [CeO_2] and silver [Ag].     

Ni2P和MoS2催化剂在二苯并噻吩加氢脱硫反应中的氢溢流效应

对分层装填的Ni₂P//MoS₂催化剂上的二苯并噻吩加氢脱硫反应进行了研究。结果表明,分层装填的Ni₂P/Al₂O₃和MoS₂/Al₂O₃催化剂在二苯并噻吩加氢脱硫反应中存在氢溢流效应,氢溢流有助于提高MoS₂催化剂的活性位密度和加氢脱硫反应速率。由于Ni₂P比NiS_x具有更强的氢分子解离能力,Ni₂P//MoS₂催化体系的氢溢流因子略高于NiS_x//MoS₂;相对于NiS_x,Ni₂P对MoS₂催化剂是更好的助剂。     

Oxidation of carbon black,propene and toluene on highly reducible Co/SBA-15 catalysts

Different cobalt loadings (3, 6, 12, 24 wt%) were impregnated using the double-solvent technique on SBA-15 calcined at 500 °C presenting a high specific surface area. The impregnated solids were stabilized at 450 °C in the air. The impregnation of cobalt led to the incorporation of cobalt oxide nanoparticles in the mesoporosity of the SBA-15. The cobalt nanoparticles were easily reducible compared to similar solids prepared by different methods. The presence of these nanoparticles enhanced significantly the reactivity of the catalysts in the considered reaction. The addition of more than 12 wt% of cobalt did not enhance the catalytic reactivity due to the deposition of cobalt oxide species on the surface of the support. The cobalt-impregnated solids are efficient in decreasing the oxidation temperature of different probe molecules and are totally selective towards the formation of CO₂ and H₂O.     

温敏性介孔复合材料PNIPAAm/SBA-15的制备与表征

采用自由基引发原位聚合(in situ polymerization)的方法合成了温敏性聚N-异丙基丙烯酰胺(PNIPAAm)/介孔分子筛SBA-15纳米复合物. 用FT-IR、XRD、TEM、低温N₂吸附-脱附、TG和DSC等手段对复合物进行了表征, 结果表明, 单体N-异丙基丙烯酰胺(NIPAAm)在介孔孔内发生了原位聚合, 聚合物PNIPAAm比较均匀地附于孔壁, 含量达24%左右. 这一聚合和孔内填充没有破坏SBA-15的有序六方结构, 但使样品的表面积、孔径、孔容减小. 同时, 这一有机-无机纳米复合物仍然保持PNIPAAm的温度响应性, 最低临界溶解温度(LCST)与纯PNIPAAm相似.