Efficient activation of the Co/SBA-15catalyst by high-frequency AC-DBD plasma thermal effects for toluene removal

Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.

Activity and Selectivity of Bimetallic Catalysts Based on SBA-15 for Nitrate Reduction in Water

Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO2 buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO2.

Preparation of B_(2)O_(3)/SBA-15 and Application as Matrix Component in Nickel-Tolerant Fluid Catalytic Cracking Catalyst

Fluid catalytic cracking(FCC)is still a key process in the modern refining industry,in which nickel contamination of the FCC catalyst can significantly increase the dry gas and coke yields and thus seriously affect the stability of the FCC unit.Therefore,in this work,B_(2)O_(3)-modified SBA-15 molecular sieves(B_(2)O_(3)/SBA-15)with different B_(2)O_(3) contents were prepared,characterized,and further used as matrix component in the preparation of Ni-tolerant FCC catalyst.The characterization results indicated that the B_(2)O_(3)/SBA-15 samples possessed excellent Ni passivation ability and kept the characteristic structure of the parent SBA-15 such as highly ordered mesopores,large surface area,and high pore volume,which enabled the B_(2)O_(3)/SBA-15 sample to greatly improve the Ni tolerance of the prepared FCC catalyst.The heavy oil catalytic cracking tests indicated that,under the same Ni contamination conditions,the dry gas,coke,and heavy oil yields of the FCC catalyst containing B_(2)O_(3)/SBA-15 decreased by 0.92%,1.65%,and 1.26%,respectively,compared with those of conventional FCC catalyst,while the total liquid yield increased by 3.83%.

Preparation and Characterization of Pt-Sn/SBA-15 Catalysts and Their Catalytic Performances for Long Chain Alkane Dehydrogenation

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%.

Effect of Ni Loading and Ce_(x)Zr_(1-x)O_(2) Promoter on Ni-Based SBA-15 Catalysts for Steam Reforming of Methane

A series of Ni/SBA-15 catalysts with Ni contents ranging from 5wt% to 20wt% as well as 10wt%Ni/10wt%CexZr1-xO2/SBA-15 （x=0, 0.5, 1） were prepared. The structures of the catalysts were characterized using XRD, TPR, TEM and BET techniques. The catalytic activities of the catalysts for steam reforming of methane were evaluated in a continuous flow microreactor. The results indicated that both the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts had good catalytic activities at at- mospheric pressure. The 10wt%Ni/SBA-15 catalyst exhibited excellent stability at 800 ℃ for time on stream of 740 h. After the reaction, carbon deposits were not formed on the surface of the catalyst. There existed a regular hexagonal mesoporous structure in the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts. The nickel species and the CexZr1-xO2 component were all confined in the SBA-15 mesopores. The CexZr1-xO2 could promote dispersion of the nickel species in the Ni/CexZr1-xO2/SBA-15 catalysts.

Effect of Cu promoter on Ni-based SBA-15 catalysts for partial oxidation of methane to syngas

A series of Ni/SBA-15 catalysts with 5wt% to 15wt% Ni content as well as a series of 12.5%Ni/Cu/SBA-15 catalysts with 1% to 10% copper content were prepared by the impregnation method. The catalytic performance for partial oxidation of methane was investigated in a continuous flow microreactor under atmospheric pressure. The textural and chemical properties of the catalysts were characterized by XRD, TEM, BET and Hz-TPR techniques. The results indicated that the catalysts modified with Cu promoter showed better performance than those without modification. For the 12.5%Ni/2.5%/Cu/SBA-15 catalyst, at 850 ℃ the conversion of CH4 reached 97.9% and the selectivity of CO and H2 reached 98.0% and 96.0%, respectively. In XRD patterns of the Ni/Cu/SBA-15 catalyst with 7.5 to 10% Cu contents there were CuO characteristic peaks beside NiO characteristic peaks. The mesoporous structure of SBA-15 was retained in all of the catalysts. TPR analysis of the catalysts revealed that a strong interaction between Ni, Cu promoter and SBA-15 support may be existed. This interaction enhanced significantly the redox properties of the catalysts resulting in the higher catalytic activity.

Effect of MgO promoter on Ni-based SBA-15 catalysts for combined steam and carbon dioxide reforming of methane

A series of Ni/SBA-15 catalysts with Ni contents ranging from 5 wt% to 15 wt%, as well as another series of 10%Ni/MgO/SBA-15 catalysts, in which the range of the MgO content was from 1 wt% to 7 wt%, were prepared, and their catalytic performances for the reaction of combined steam and carbon dioxide reforming of methane were investigated in a continuous flow microreactor. The structures of the catalysts were characterized using the XRD, H2-TPR and CO2-TPD techniques. The results indicated that the CO selectivity for this reaction was very close to 100%, and the H2/CO ratio of the product gas could be controlled by changing the H2O/CO2 molar ratio of the feed gas. The simultaneous and plentiful existing of steam and CO2 had a significant influence on the catalytic performance of the 10%Ni/SBA-15 catalyst without modification. After reacting at 850 °C for 120 h over this catalyst, the CH4 conversion dropped from 98% to 85%, and the CO2 conversion decreased from 86% to 53%. However, the 10%Ni/3%MgO/SBA-15 catalyst exhibited a much better catalytic performance, and after reacting for 620 h, the CO2 conversion over this catalyst dropped from 92% to around 77%, while the CH4 conversion was not decreased. Oxidation of the Ni0 species as well as carbon deposition during the reaction were the main reasons for the deactivation of the catalyst without modification. On the other hand, modification by the MgO promoter improved the dispersion of the Ni0 species, and enhanced the CO2 adsorption affinity which in turn depressed the occurring of carbon deposition, and thus retarded the deactivation process.

Effect of O_2 and H_2O on the tri-reforming of the simulated biogas to syngas over Ni-based SBA-15 catalysts

A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method.The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a continuous flow fixed-bed micro-reactor.The stability of the catalyst was tested at 800 ？C.The results indicated that 10wt%Ni/SBA-15 catalyst exhibited the highest catalytic activities for the combined reforming of the simulated biogas to syngas.Under the reaction conditions of the feed gas molar ratios CH4/CO2/O2/H2O = 2/1/0.6/0.6,GHSV = 24000 ml·gcat^-1·h^-1 and the reaction temperature T = 800 ℃,the conversions of CH4 and CO2 were 92.8% and 76.3%,respectively,and the yields of CO and H2 were 99.0% and 82.0%,respectively.The catalytic activities of the catalyst did not decrease obviously after 100 h reaction time on stream.

Preparation,Structure Characterization and Hydrodesulfurization Performance of B-Ni_2P/SBA-15/Cordierite Monolithic Catalysts

A series of B-Ni2P/SBA-15/cord monolithic catalysts were prepared by coating the slurry of the B-Ni2P/SBA-15 precursors on a pretreated cordierite support, and followed by temperature-programmed reduction in a H2 flow. The samples were characterized by X-ray diffraction （XRD） and N2 adsorption-desorption technique. The catalytic activities for the hydrodesulfurization （HDS） of dibenzothiophene （DBT） were evaluated. The results showed that Ni2P phase was present in all B-Ni2P/SBA-1 5/cord monolithic catalysts. The specific surface areas （SBET） of the B-Ni2P/SBA-15/cord monolithic catalysts was first increased to 167 m2· g-1, and then decreased to 155 m2· g-1 with the increase of boron contents. The catalytic activity also showed the similar trend with the increase of boron contents. The 1.75% （by mass） B-Ni2P/SBA-15/cord monolithic catalysts exhibited the highest DBT conversion of 98.4% at 380 ℃. The cordierite-based monolithic catalysts showed better low temperature sensitivity for HDS of DBT in comparison with the particle catalysts. Moreover, two HDS routes, direct desulfurization （DDS） and hydrogenation （HYD）, proceeded independently over B-Ni2P/SBA-15/cord monolithic catalysts and the main pathway was DDS.

Ruthenium promotion of Co/SBA-15 catalysts for Fischer-Tropsch synthesis in slurry-phase reactors

The aim of this work was to evaluate the catalytic properties of a Ru promoted Co/SBA-15 catalyst for Fischer-Tropsch synthesis （FTS）. The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction and transmission electron microscopy. The Fischer-Tropsch synthesis using the catalyst was carried out to evaluate the catalyst activity and its effect on FTS product distribution. The synthesis was carried out in a slurry reactor operating at 513 K, 20 atm, CO ： H2 molar ratio of 1 ： 1. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present in the form of Co3O4 in the catalyst. The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve. Fischer-Tropsch synthesis activity and C5＋ hydrocarbon selectivity increased with the addition of Ru. The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co. Ru/Co/SBA-15 catalysts showed moderate conversion （40%） and high selectivity towards the production of C5＋ （80 wt%）.

Propane Dehydrogenation on PtSnNa/AlSBA-15 Catalyst:Influence of Tin as a Promoter

PtSnNa/AlSBA-15 catalysts with different amounts of Sn were prepared for propane dehydrogenation.The catalysts were characterized by XRF,BET,H2 chemisorption,NH3-TPD,H2-TPR,and TPO techniques.Test results indicated that the presence of tin not only modified the acid function and the interfacial character between metal and support,but also reduced the coke deposition effectively.Among these catalysts investigated thereby,the PtSn(0.7%)Na/AlSBA-15 catalyst had the best catalytic performance in terms of propane conversion and stability.With the continuous addition of Sn,more amounts of Sn0 species appeared,which was unfavorable to the reaction.The PtSn(0.7%)Na/AlSBA-15 catalyst was parametrically characterized in order to obtain necessary information to integrate the process operating conditions.A weight hourly space velocity of 3 h-1,a reaction temperature of 610 ℃ and a H2/C3H8 molar ratio of 0.25 were found to be optimum conditions for achieving a higher dehydrogenation activity of the catalyst.

Selective oxidation of ethane to aldehydes over SBA-15 supported molybdenum catalyst

SBA-15 supported Mo catalysts （Moy/SBA-15） were prepared by an ultrasonic assisted incipient-wetness impregnation method. The physical and chemical properties of the catalysts were characterized by means of N2-adsorption-desorption, XRD, TEM, UV-Vis, Raman, XANES and H2-TPR. The results showed that a trace amount of MoO3 was produced on high Mo content samples. Tum-over frequency （TOF） and product selectivity are dependent on the molybdenum content. Both Mo0.75/SBA-15 and Mo1.75/SBA-15 catalysts give the higher catalytic activity and the selectivity to the total aldehydes for the selective oxidation of C2H6. At the reaction temperature of 625℃, the maximum yield of aldehydes reached 4.2% over Mo0.75/SBA-15 catalyst. The improvement of the activity and selectivity was related with the state of MoOx species.

CrO_x/SBA-15介孔催化剂上丙烷在二氧化碳气氛中脱氢反应的研究

The structure and catalytic properties based on Chromium Oxide supported on mesoporous SBA-15 for oxidative dehydrogenation of propane by CO2 have been studied by using X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and propane pulsing experiments in the absence of gas-phase O2. It has been shown that propane conversion and propene yield increase with Cr loadings. The propane conversion and propene yield on CrOx (Cr: 10wt%)/SBA-15 catalyst for oxidative dehydrogenation of propane by CO2 at 550 ℃ reach 24.8% and 21.8%, respectively .The results of ESR, UV-Vis DRS and propane pulsing experiments indicate that CrⅢ in the CrOx / SBA-15 catalyst is the main active species in oxidative dehydrogenation of propane by CO2 and CrⅥ, CrⅤ is inactive in dehydrogenation.

可重复使用的丙磺酸功能化纳米结构SBA-15上醇和酚与六甲基二硅氮烷的硅烷化反应(英文)

Various alcohols and phenols were trimethylsilylated in excellent yields using hexamethyldisilazane in the presence of catalytic amounts of environmentally friendly, hydrophobic, highly thermal stable, and completely heterogeneous sulfonic acid functionalized mesostructured SBA-15 in dichloromethane at ambient temperature. Primary, bulky secondary, tertiary, and phenolic hydroxyl functional groups were transformed to the corresponding trimethylsilyl ethers in excellent yields. The simple experimental procedure was accompanied by easy recovery and the catalyst was reusable (at least 18 reaction cycles); these are attractive features of this protocol.

Dehydrogenation of Isobutane to Isobutene with Carbon Dioxide over SBA-15-Supported Chromia-Ceria Catalysts

A series of SBA-15-supported chromia-ceria catalysts with 3% Cr and 1%--5% Ce （3Cr-Ce/SBA） were pre- pared using an incipient wetness impregnation method. The catalysts were characterized by XRD, N2 adsorption, SEM, TEM-EDX, Raman spectroscopy, UV-vis spectroscopy, XPS and H2-TPR, and their catalytic performance for isobutane dehydrogenation with CO2 was tested. The addition of ceria to SBA-15-supported chromia improves the dispersion of chromium species. 3Cr-Ce/SBA catalysts are more active than SBA-15-supported chromia （3Cr/SBA）, which is due to a higher concentration of Cr^6＋ species present on the former catalysts. The 3Cr-3Ce/SBA catalyst shows the highest activity, which gives 35.4% isobutane conversion and 89.6% isobutene selectivity at 570℃ after 10 min of the reaction.

Ni-W Catalysts Supported on Mesoporous SBA-15: Trace W Steering CO_(2) Methanation

A series of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(NixW/SBA-15, Ni-5%, x=1, 10, 50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), transmission electronic microscopy(TEM), H2-temperature programmed reduction(H2-TPR), and X-ray photoelectron spectroscopy(XPS). High-resolution TEM images, XPS measurements, H2-TPR experiments coupled with PXRD results determined the evolution of Ni and W species. It is found that a trace amount of W from H2WO4 can significantly improve Ni dispersion on SBA-15 (Ni50W/SBA-15) with Ni0 and non-stoichiometric WOx species as small as ca. 3.6 nm. The prepared NixW/SBA-15 was utilized for CO_(2) hydrogenation, which showed that a higher W content restrained the CO_(2) hydrogenation while a lower W ratio promoted both conversion rate and selectivity for methane compared with Ni/SBA-15. The Ni50W/SBA-15 catalyst showed the best performance with a 93.3% CO_(2) conversion rate and 99.7% selectivity for methane at 400 oC under 0.1 MPa and maintained ca. 97% initial performance for 24 h. Tracking product evolution experiments by in-situ Fourier transform infrared spectrascopy(FTIR) indicated that a small amount of W can modify the surface of Ni particles by geometric coverage and electronic modification, which facilitates the adsorption of the CO intermedia and results in the formation of CH4. This work provides a new clue to fabricating efficient CO_(2) conversion bimetallic materials.

Characterization and Dehydrogenation Activity of SBA-15 and HMS Supported Chromia Catalysts

SBA-15 and HMS supported chromia catalysts were prepared and characterized. Chromia is highly dispersed on the mesoporous supports when its loading is 7 wt%. The supported catalysts display high activity, selectivity and stability for dehydrogenation of ethylbenzene and propane. ESR measurement of the catalysts before and after reaction shows that the active species for dehydrogenation reaction might be Cr3+ species on the catalyst surface, and the activity of the catalyst is probably correlated with the dispersion of Cr3+ species.

Preparation and application of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide

A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh_3-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.

Asymmetric transfer hydrogenation of prochiral ketone catalyzed over Fe-CS/SBA-15 catalyst

A heterogeneous chiral catalyst Fe(III)-CS(chitosan)complex/mesoporous molecular sieve SBA-15(Santa Barbara Amorphous)was prepared.The asymmetric transfer hydrogenations of prochiral acetophenone and 4-methyl-2-pentanone to corresponding chiral alcohols were carried out on Fe-CS/SBA-15 at atmosphere pressure using 2-propanol as hydrogen donor.Effects of Fe content in cata-lyst,reaction temperature,reaction time and promoter KOH concentration on the conversion of substrates and enantio-selectivity were investigated.Fe-CS/SBA-15 with 2.2%mass fraction Fe exhibits considerable enantioselectivity and cata-lytic activity for the asymmetric transfer hydrogenations of aromatic ketone and aliphatic ketone.Under optimal reaction conditions:KOH concentration 0.03 mol/L,reaction tem-perature 70℃ and reaction time 4 h,enantiomer excess(ee)of(R)-1-phenylethanol and conversion of acetophenone can reach 87.4%and 27.7%,respectively.Under the above KOH concentration and reaction temperature and reaction time of 8 h,the ee of(R)-4-methyl-2-pentanol and conversion 4-methyl-2-pentanone amounted to 50.2%and 25.5%,respectively.

Effect of the pore size of Co/SBA-15 isomorphically substituted with zirconium on its catalytic performance in Fischer-Tropsch synthesis

Cobalt catalysts supported on a series of mesoporous SBA-15 materials isomorphically substituted with zirconium (Zr/Si atomic ratio=1/20) with different pore sizes (5.7 nm,7.8 nm,11.6 nm,17.6 nm) have been synthesized.The catalysts were characterized by transmission electron microscopy,29 Si solid state magic angle spinning (MAS)NMR,N2 adsorption-desorption measurements,X-ray powder diffraction,X-ray photoelectron spectroscopy,H2-temperature programmed reduction,H2-temperature programmed desorption and O2 titrations.The results indicated that larger pore size led to weaker interactions between cobalt and the supports which lowered the temperature of both reduction steps (Co3O4 → CoO and CoO→ Co0).The catalytic performances of the catalysts in Fischer-Tropsch synthesis (FTS) were tested in a fixed bed reactor.It was found that the FTS catalytic activity and product selectivity depended strongly on the pore size of the catalysts.The catalyst with a pore size of 7.8 nm showed the best FTS activity,and the catalyst with a pore size of 17.6 nm showed the highest selectivity to C12-C20 and C20+ hydrocarbons.