Ultra‐deep desulfurization of a model fuel using novel VOHPO4 0.5H2O/boehmite catalysts

A high‐surface‐area boehmite was used as the support for a series of vanadium phosphate catalysts. The catalysts were prepared by heating of V₂O₅ in an isobutyl alcohol and benzyl alcohol mixture at 140°C for 5 h to reduce V⁵⁺ to more active V⁴⁺ in the presence of phosphoric acid. Then a series of catalysts with various VPO loadings on boehmite were synthesized. The catalysts were characterized using various techniques. The catalysts were utilized for extraction combined with catalytic oxidation of dibenzothiophene. The important factors influencing the desulfurization process, including reaction time, temperature, H₂O₂, catalyst loading, catalyst amount and solvents, were systematically investigated. Under the optimized reaction conditions, i.e. 30 mg of catalyst loading at 50°C and in 60 min, sulfur removal reached 94%. The catalyst was recycled and reused five times.     

Sulfonated porous biomass-derived carbon with superior recyclability for synthesizing ethyl levulinate biofuel

The synthesis of ethyl levulinate (EL) via esterification of levulinic acid (LA) with ethanol, which can be derived from biomass, has become an attractive topic since EL can be applied in many fields, such as fuel additives for petroleum and biodiesel, food additives and fragrance. Herein, the sulfonated porous carbon catalysts derived from the rinds of corn stalk biomass wastes were prepared by using sulfuric acid and phosphoric acid as the sulfonating agent and activator, respectively. The preparation parameters were optimized based on the catalytic activity for LA esterification with ethanol and the acid density of the corresponding catalysts. Also, various reaction factors were optimized to improve the catalytic efficiency over the optimal sulfonated corn stalk-derived carbon (s-CSC). Under the conditions of reaction temperature 80 °C, catalyst dosage 5 wt%, ethanol-to-LA molar ratio 5.0:1 and reaction time 8 h, the LA conversion reached 94% and 93% catalyzed by s-CSC and the optimal porous catalyst (s-p-CSC), respectively. Noticeably, benefitting from the hierarchical porous structure with large surface area, s-p-CSC exhibited much better recyclability than s-CSC. This work offers a highly effective solid acid catalyst for the synthesis of biofuel.

     

Synergistic effect of Zr-incorporated framework and subsequent deposition of PEHA towards efficient and reusable HPW/PEHA/ZrSBA-15 composites

Heteropolyacid-based catalysts with molecular level distributions of surface functionalities were synthesized by anchoring phosphotungstic acid (HPW) onto the pentaethylenehexamine (PEHA) layers stabilized by platelet ZrSBA-15 with short mesochannels. Namely, the presence of zirconium species in pore walls could significantly improve the surface acidity to attract and stabilize PEHA species, leading to a stronger interaction between them and a superiority to make HPW species highly stable. Standard characterizations of XRD, SEM, TEM, FT-IR, TG, N₂ adsorption–desorption and N elemental analyses were preserved to demonstrate the synergistic effect. The resulting composite were investigated for the oxidation of benzaldehyde to benzoic acid in the H₂O₂-mediated environment, the catalyst 25 % HPW/PEHA/ZrSBA-15 screened high yield for benzoic acid (~99.7 %). Besides, various reaction parameters such as reaction temperature, reaction time, the amount of hydrogen peroxide and catalyst reusability were also investigated for the oxidation of benzaldehyde to benzoic acid with a target to confirm the validity of the catalyst.     

Efficient and Reusable Sn(II)‐containing Imidazolium‐based Ionic Liquid as a Catalyst for the Oxidation of Benzyl Alcohol

A simple and efficient catalytic system [BBIM]Br–SnCl₂ for the oxidation of benzyl alcohol using hydrogen peroxide as the oxidant has been developed. Reaction conditions such as the catalyst dose, the solvents, reaction temperature, reaction time, and the amount of hydrogen peroxide were investigated. The optimum reaction conditions identified were 0.11 g of catalyst, no solvent, 65°C, 15 min, and 2 mmol of hydrogen peroxide. Oxidation of various alcohols was also investigated under the optimized conditions. The catalyst [BBIM]Br–SnCl₂ can be easily recovered and reused for six reaction runs without significant loss of catalytic activity, because the Sn species of the catalyst can be coordinated with the imidazole ring of the ionic liquid. The reused catalyst was further characterized by Fourier transform infrared spectroscopy to evaluate its chemical properties. The results proved that the [BBIM]Br–SnCl₂ catalyst was stable and reusable for the oxidation reactions. A possible mechanism for the oxidation of benzyl alcohol to benzaldehyde is proposed.     

Novel Dendritic PNP Chromium Complexes: Synthesis,Characterization, and Performance on Ethylene Oligomerization

Three dendritic PNP ligands with ethylenediamine, 1,4‐butanediamine, 1,6‐diaminohexane as bridged groups are synthesized in good yields, respectively. Three dendritic PNP chromium complexes ( C1  –  C3 ) are prepared with the ligands and chromium(III ) chloride tetrahydrofuran complex (CrCl₃(THF )₃) as materials. The dendritic PNP ligands and the synthetic chromium complexes are fully characterized by spectroscopic and analytical methods. All chromium complexes activated with methylaluminoxane (MAO ) exhibited moderate activities on ethylene oligomerization (7.90 × 10⁴ – 2.15 × 10⁵ g (mol Cr h)⁻¹] and had better selectivity for C₆ and C₈ oligomer, reaching up to 81%. The chromium complex ( C1 ) activated with diethylaluminium chloride (Et₂AlCl) has higher catalytic activity than the chromium complex C1 activated with MAO , although the chromium complex ( C1 ) activated with Et₂AlCl had lower selectivity for C₆ and C₈ oligomer. The effects of solvent and reaction parameters on ethylene oligomerization are also studied using the chromium complex C1 as pre ‐ catalyst and MAO as co ‐ catalyst. Under optimized conditions ([complex] = 2 μmol, Al/Cr = 500, 25 °C, 0.9 MP a ethylene, 30 min), the catalytic activity of complex C1 in toluene is 2.15 × 10⁵ g (mol Cr h)⁻¹ and the selectivity for C₆ and C₈ oligomer is 36.76%. In addition, the structure of complexes significantly affects both the catalytic activity and the selectivity on ethylene oligomerization.     

One pot synthesis of chromium incorporated SBA-16 under acid medium-Application in the selective oxidation of benzyl alcohol derivatives

Cr-SBA-16 mesoporous silica heterogeneous catalysts (Si/Cr = 7, 14, and 28) were successfully synthesized by one-pot hydrothermal method at low acidic medium. The catalysts were characterized by means of X-ray diffraction (XRD), N₂ adsorption-desorption at 77 K, Fourier Transform Infrared (FTIR), X-ray photoelectron (XPS) and Diffuse Reflectance UV–Vis (DRS) Spectroscopies, Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. Herein, Cr-SBA-16 catalysts are evaluated in the selective catalytic oxidation of benzyl alcohol derivatives using H₂O₂ as oxidant. From XPS and UV–Vis (DRS) spectroscopies the molar ratios between Cr⁶⁺/Cr³⁺ are found to increase versus chromium loading in the following order: Cr-SBA-16(28) < Cr-SBA-16(14) < Cr-SBA-16(7). Hence the highest Cr⁶⁺ in tetrahedrally environment is observed for Si/Cr = 7. We demonstrated for the first time that the selective catalytic oxidation of benzyl alcohol (BzOH) using H₂O₂ over Cr-SBA-16 occurs through noncompetitive adsorption mechanism and the reaction is pseudo-first order to BzOH. The activity of the reaction depends on the symmetry of chromium species, herein, high activity is observed for tetrahedral chromium species in Cr-SBA-16(7). The absence of any chromium ions in the filtrate shows no chromium leaching from the silica framework.     

Low-Temperature Catalytic Oxidation of Sulfide Ions in Aqueous Solutions on a Ni-Oxide System

Catalytic oxidation of sulfide ions in aqueous solutions by air oxygen has been investigated using a Ni-oxide system as a catalyst. The kinetics and the selectivity of the oxidation process were studied by varying the pH, catalyst amount and reaction temperature. A reduction/oxidation mechanism of the reaction has been supposed comprising interaction between the surface active oxygen of the catalyst and HS^– and reoxidizing of the reduced catalyst by the dissolved oxygen. The results obtained show that the Ni-oxide system is a promising catalyst for practical application.     

Studies on kinetics and thermodynamics of oxidation of 3,4,5-trimethoxy benzaldehyde,benzaldehyde and N,N-dimethylamino benzaldehyde by tetraethylammonium bromochromate in dimethyl formamide and acetic acid mixture

The oxidation of 3,4,5-trimethoxy benzaldehyde (TMBA), benzaldehyde (BA) and dimethylamino benzaldehyde (DMABA) in N,N-dimethyl formamide (DMF) by tetraethylammonium bromochromate (TEABC) resulted in the formation of the corresponding acids. The reaction is first order with respect to both TEABC and the aldehydes. The reaction is catalyzed by toluene-p-sulfonic acid (p-TsOH). The hydrogen ion dependence has the form: k_obs = a + b [H⁺]. The reaction has been studied in different percentage of DMF–acetic acid mixture. The effect of dielectric constant of the medium indicates the reaction to be of ion–dipole type. Various thermodynamic parameters for the oxidation have been reported and discussed along with the validity of isokinetic relationship. Reason for high rate in the case of oxidation of N,N-dimethylamino benzaldehyde is also described. A mechanism involving formation of a chromate ester intermediate in the slow step has been proposed.     

Room temperature synthesis of Ti-SBA-15 from silatrane and titanium-glycolate and its catalytic performance towards styrene epoxidation

A novel room temperature sol–gel synthesis of Ti-SBA-15 is described using moisture stable silatrane and titanium glycolate precursors, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (EO₂₀PO₇₀EO₂₀) as the structure directing agent. Catalyst performance was optimized by systematically investigating the influence of acidity, reaction time and temperature, and titanium loading. Small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) showed well-ordered 2D mesoporous hexagonal structures, while N₂ adsorption/desorption measurements yielded high surface areas (up to 670 m²/g), with large pore diameters (5.79 nm) and volumes (0.83 cm³/g). Diffuse reflectance UV–visible spectroscopy (DRUV) was found that tetravalent titanium as Ti⁴⁺O₄ tetrahedra were incorporated in the framework through displacement of Si⁴⁺O₄ after calcination (550°C/6 h) to loadings of 7 mol% Ti without perturbation of the ordered mesoporous structure, or decoration by extra-framework anatase containing Ti⁴⁺O₆ octahedra. The catalytic activity and selectivity of styrene epoxidation using hydrogen peroxide (H₂O₂) showed that the conversion of styrene increases significantly at higher titanium contents. The only products of this reaction were styrene oxide and benzaldehyde, with selectivity of 34.2 and 65.8%, respectively, at a styrene conversion of 25.8% over the 7 mol% Ti-SBA-15 catalyst. Beyond this titanium loading, anatase is deposited on the framework and catalytic activity degrades. The performance of the new catalyst is also shown to be superior to conventional materials produced by incipient wetness impregnation where Ti resides on the surface of SBA-15, giving a styrene conversion of 11.9% under identical reaction conditions.     

Ag/SBA-15低温气相选择性催化氧化苯甲醇合成苯甲醛

以SBA-15为载体,采用浸渍法制备了不同Ag含量的Ag/SBA-15,通过N₂吸附-脱附、X射线衍射、扫描电子显微镜、高分辨透射电子显微镜、X射线光电子能谱和电感耦合等离子体质谱对催化剂进行了表征。将Ag/SBA-15用于苯甲醇气相选择性催化氧化合成苯甲醛,研究了反应条件对转化率和选择性的影响。结果表明,Ag/SBA-15具有均一的一维孔道结构、较厚的孔壁（3-5 nm）及较大的比表面积（411-541 m²/g）,其规整纳米空间的限域作用使一定负载量的Ag以纳米尺寸均匀分散于介孔SBA-15孔道内,增加了活性组分的比表面积。亲核性氧物种从Ag到SBA-15表面的氧溢流,提高了低温下Ag/SBA-15对苯甲醇气相选择性氧化合成苯甲醛的催化性能。5.3% Ag/SBA-15中的Ag粒径为5-6 nm,且均匀分散于载体孔道中,反应温度为220℃时,苯甲醇转化率为87%,苯甲醛选择性为95%;240℃时,苯甲醇转化率和苯甲醛选择性分别高达94%和97%;并在240-300℃范围内,其催化活性和选择性保持不变,表现出了良好的温度耐受能力。催化剂经活化再生可以连续使用40 h,选择性基本保持不变。     

Selective oxidation of ethylbenzene to acetophenone over Cr(III) Schiff base complex intercalated into layered double hydroxide

A new heterogeneous catalyst, Cr(III) Schiff base‐containing layered double hydroxide, was synthesized using the intercalation method. The Cr(III) Schiff base complex derived from 2‐hydroxy‐1‐naphthaldehyde and 4‐aminobenzoic acid was intercalated into the layered double hydroxide. The synthesized materials were characterized using inductively coupled plasma atomic emission spectrometry, energy‐dispersive X‐ray analysis, scanning electron microscopy, X‐ray diffraction, Brunauer–Emmett–Teller surface area measurement, Fourier transform infrared spectroscopy, thermogravimetric analysis, diffuse reflectance UV–visible spectroscopy and electron paramagnetic resonance spectroscopy. The catalytic activity was investigated for the oxidation of ethylbenzene with tert‐butylhydroperoxide as an oxidant under solvent‐free conditions as well as with lower chromium concentrations. In the oxidation reaction, ethylbenzene was oxidized to acetophenone and benzaldehyde. The catalyst was recycled ten times without significant loss of catalytic activity. Leaching studies performed with hot filtration experiments showed that the chromium catalyst was heterogeneous in nature and stable under the reaction conditions.     

Construction of Cu-Ce interface for boosting toluene oxidation: Study of Cu-Ce interaction and intermediates identified by in situ DRIFTS

A facile hydrothermal method was applied to gain stably and highly efficient CuO-CeO₂ (denoted as Cu1Ce2) catalyst for toluene oxidation. The changes of surface and inter properties on Cu1Ce2 were investigated comparing with pure CeO₂ and pure CuO. The formation of Cu-Ce interface promotes the electron transfer between Cu and Ce through Cu²⁺ + Ce³⁺ ↔ Cu⁺ + Ce⁴⁺ and leads to high redox properties and mobility of oxygen species. Thus, the Cu1Ce2 catalyst makes up the shortcoming of CeO₂ and CuO and achieved high catalytic performance with T₅₀ = 234 °C and T₉₉ = 250 °C (the temperature at which 50% and 90% C₇H₈ conversion is obtained, respectively) for toluene oxidation. Different reaction steps and intermediates for toluene oxidation over Cu1Ce2, CeO₂ and CuO were detected by in situ DRIFTS, the fast benzyl species conversion and preferential transformation of benzoates into carbonates through C=C breaking over Cu1Ce2 should accelerate the reaction.     

Condensation reaction of 3-(methacryloxypropyl)-trimethoxysilane and diisobutylsilanediol in non-hydrolytic sol-gel process

The condensation reaction of 3-methacryloxypropyl-trimethoxysilane (MPTS) and diisobutylsilanediol (DIBSD) in a non-hydrolytic sol-gel process was investigated in terms of the reaction time and the catalyst amount for fabrication of inorganic-organic hybrid materials. The degree of condensation, which was characterized by ²⁹Si NMR, ¹H NMR and Abbe refractometry, increases with increased the reaction time and greater catalyst amount. However, a the large catalyst amount breaks the methacryl group during the condensation reaction. Thus, the reaction time and the catalyst amount were optimized to synthesize the condensed methacryl oligosiloxanes.     

Realizing porphyrin‐functionalization of crosslinked polystyrene microspheres via two special polymer reactions

A novel route to make crosslinked polystyrene (CPS) microspheres to be porphyrin‐functionalized via two special polymer reactions, Kornblum reaction and Adler reaction, was designed and founded. The chloromethyl groups of chloromethylated crosslinked polystyrene (CMCPS) microspheres were first oxidized to aldehyde groups by dimethyl sulfoxide as oxidant via Kornblum oxidation reaction, obtaining aldehyde group‐modified microspheres, ALCPS microspheres, in which, a great quantity of benzaldehyde groups suspend from the main chain, and the effects of the main factors including the reaction temperature, the addition of KI as catalyst and the used amount of NaHCO₃ as acid acceptor on the oxidation reaction were examined. Subsequently, the synchronic synthesizing and immobilizing of porphyrins on CPS microspheres were carried out via the Adler reaction between solid and liquid phases, in which, ALCPS microspheres, pyrrole and benzaldehyde or benzaldehyde analog in a solution were used as co‐reactants, resulting in porphyrin‐functionalized microspheres, and the influence of diverse factors including the acidity of the protonic acid catalyst, the substituent structure of benzaldehyde analog, and the polarity of the solvent as well as the swelling property of the solvent for CPS microspheres on the process of synchronously synthesizing and immobilizing porphyrins on CPS microspheres were investigated in depth. The experimental results indicate that via the designed route, the porphyrin‐functionalization of CPS microspheres can successfully be realized. For the Kornblum oxidation reaction, under the optimal reaction conditions, the conversion of chloromethyl groups can reach 90%. For the Adler reaction between solid and liquid phases, the fitting protonic acid catalyst is lactic acid, appropriate solvent is a mixture of dimethyl sulfoxide and xylene, and using 4‐chlorobenzaldehyde as a benzaldehyde analog reactant in the solution is in favor of the porphyrin‐functionalization of CPS microspheres. Under these specific conditions, the immobilized amount of porphyrin can get up to 23.33 mmol/100 g. Copyright © 2011 John Wiley & Sons, Ltd.     

Selective ethylene oligomerization bearing hyperbranched bispyridylamine chromium catalyst

Two new hyperbranched bispyridylamine ligands and multinuclear chromium complexes were synthesized with 1.0?G hyperbranched macromolecules, 2-chloropyridine, 2-chloro-4-methylpyridine and CrCl₃(THF)₃ as raw materials. The structures of hyperbranched ligands and chromium complexes were characterized by UV, FT-IR, ¹H NMR, ESI-MS, and elemental analysis. These hyperbranched chromium complexes were evaluated as catalyst precursors by using MAO as activator in the oligomerization of ethylene. Effects of reaction temperature, reaction pressure, Al/Cr molar ratio, concentration of catalyst, solvent, and the structure of catalysts on the catalytic activity and product selectivity were investigated. The oligomerization results showed that with increase of reaction temperature, reaction pressure, and Al/Cr molar ratio, the catalytic activity increased and then decreased; the catalytic activity continuously decreased as the amount of catalyst increased. The products were mainly based on C₆ and C₈. Under optimized conditions, the catalytic system of hyperbranched NNN/Cr(III)/MAO led to activity of 1.26?×?10⁵ g/(mol·Cr·h) and 63.34% selectivity for C₆ and C₈.     

Pd/PMO-SBA-15 催化剂催化苯甲醇选择氧化反应性能

 研究了 PMO-SBA-15 材料负载的金属钯纳米粒子 (Pd/PMO-SBA-15) 在水相中催化苯甲醇选择氧化制苯甲醛的反应. 考察了纳米粒子种类、氧化剂用量、反应时间和反应温度等对苯甲醇转化率及苯甲醛选择性的影响. 结果表明, 以水为溶剂, 以 H2O2 (30%) 为氧化剂时, 可得到较高的苯甲醇转化率和苯甲醛选择性. 当以 0.05 g 的 2%Pd/PMO-SBA-15 为催化剂, H2O2 用量为 1.5 ml, 反应温度为 80 oC, 反应 4 h 时, 苯甲醇转化率和苯甲醛选择性分别达到 97.1% 和 100.0%. 对该催化体系的重复使用性能进行了考察. 结果发现, 随着使用次数的增加, 苯甲醇转化率有所下降, 但苯甲醛选择性保持不变.     

Preparation and catalysis of chloromethylated polystyrene‐supported macrocyclic Schiff base metal complexes for the oxidation of cumene

Chloromethylated polystyrene‐supported macrocyclic Schiff base metal complexes (PS‐L‐M, M = Cu²⁺, Co²⁺, Ni²⁺, and Mn²⁺) were synthesized and characterized by the methods of IR, ICP, and small area X‐ray photoelectron spectroscopy (XPS). The oxidation of cumene by molecular oxygen in the absence of solvent with the synthesized complexes employed as catalyst was carried out. In comparison with their catalytic activities, PS‐L‐Cu is a more effective catalyst for the oxidation of cumene. The main products are 2‐phenyl‐2‐propanol (PP) and cumene hydroperoxide, which were measured by GC/MS. The influences of reaction temperature, the amount of catalyst, as well as the reaction time on the oxidation of cumene were investigated. Copyright © 2008 John Wiley & Sons, Ltd.     

金属次卟啉二甲酯催化氧化苯乙烯制苯甲醛

将金属次卟啉二甲酯用作叔丁基过氧化氢（TBHP）氧化苯乙烯制苯甲醛的催化剂。 考察了催化剂、氧化剂用量、反应温度、时间、溶剂和不同金属次卟啉二甲酯[M(DPDME)]对苯乙烯转化率及苯甲醛选择性的影响,初步探索了反应机理。 结果表明,金属次卟啉二甲酯能够顺利地选择性催化氧化苯乙烯生成苯甲醛。 以0.002 mmol锰次卟啉二甲酯[ClMn(DPDME)]为催化剂,0.4 mmol TBHP为氧化剂,1 mmol苯乙烯为底物,5 mL CH3CN/H2O(体积比4∶1)为溶剂,反应温度75 ℃,常压反应20 h,苯乙烯的转化率达到98.3%,苯甲醛的选择性为92.7%。     

Aqueous treatment of single-walled carbon nanotubes for preparation of Pt–Fe core–shell alloy using galvanic exchange reaction: Selective catalytic activity towards oxygen reduction over methanol oxidation

We have demonstrated a new, cost effective synthesis of single-walled carbon nanotube supported Pt–Fe core–shell alloy catalyst (Pt–Fe/SWNT) for the direct methanol fuel cell using galvanic exchange reaction. The Pt–Fe/SWNTs have shown much larger Pt active surface area (150 m²/g-Pt) than the commercial catalyst (54 m²/g-Pt). Furthermore, four-fold enhancement of catalytic activity of the Pt–Fe/SWNTs for oxygen reduction reaction (ORR) has been observed. This catalyst has also demonstrated its tolerance to methanol in ORR.     

镍铁氰化物纳米粒子的合成及其多相催化无溶剂条件下苯甲醇氧化的潜能(英文)

Nickel hexacyanoferrate nanoparticles were synthesized and characterized using elemental analysis, thermal analysis, infrared spectroscopy, and X-ray diffraction. A FE-SEM image of the nickel hexacyanoferrate showed that it consists of nearly spherical particles with sizes ranging from 30 to 70 nm. The synthesized material was found to be a heterogeneous catalyst useful for the solvent-free oxidation of benzyl alcohol with H2O2 as an oxidant. A 36% conversion of benzyl alcohol to benzaldehyde was achieved under optimized reaction conditions using specific parameters such as the amount of catalyst, the temperature, the benzyl alcohol to H2O2 molar ratio, and the reaction time.