Effect of Competitive Adsorbates on the Catalytic Activity of H3PMo12O40@C in the Oxidation of NMST to NMSBA

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Hua-jie Liu ◽  
Zhou-wen Fang ◽  
Xin-zhi Zhou ◽  
Xiang-li Long
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Competitive Adsorption ◽  
Phosphomolybdic Acid ◽  
Catalytic Performance ◽  
Good Dispersion ◽  
Tem Characterization ◽  
Negative Effect ◽  
Impregnation Solution

AbstractThe effect of competitive adsorption on the catalytic performance of H3PMo12O40@C catalyst for producing 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) from the oxidation of 2-nitro-4- methylsulfonyltoluene (NMST) by oxygen in acetic acid has been investigated. Six kinds of acids were added into the impregnation solution as competitive adsorbates for phosphomolybdic acid in the preparation of H3PMo12O40@C catalyst. H2SO4, HCl, HNO3, CH3COOH and H2C2O4 are beneficial to improving the catalytic activity of the H3PMo12O40@C catalyst. The corresponding optimum impregnation concentrations for H2SO4, HCl, HNO3, CH3COOH and H2C2O4 are 0.4, 0.3, 0.3, 1.0 and 0.3 mol L−1, respectively. The addition of H3PO4 exerts a negative effect on the catalytic capability of H3PMo12O40@C catalyst. The results of TEM characterization show that good dispersion of H3PMo12O40 on the surface of the H3PMo12O40@C catalyst is beneficial to ameliorating the catalytic ability of H3PMo12O40@C catalyst in the production of NMSBA from NMST by oxygen in acetic acid. The results of NH3-TPD indicate that the acidity of the H3PMo12O40@C also favors the improvement of the catalytic capability of H3PMo12O40@C in the oxidation of NMST to NMSBA.

scholarly journals Effect of Fe Additives on the Catalytic Performance of Ion-Exchanged CsX Zeolites for Side-Chain Alkylation of Toluene with Methanol

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 829 ◽  
Author(s):  
Zhang ◽  
Yuan ◽  
Miao ◽  
Li ◽  
Shan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Performance ◽  
High Yield ◽  
Side Chain ◽  
Impregnation Method ◽  
Basic Sites ◽  
Lewis Acidic Sites ◽  
X Zeolite ◽  
Acidic Sites ◽  
Negative Effect

The side-chain alkylation of toluene with methanol was investigated over some Fe-modified Cs ion-exchanged X zeolite (CsX) catalysts prepared via the impregnation method using different iron sources. The absorption/activation behaviors of the reactants on the surface of the catalysts were studied by in situ Fourier-transform infrared (FT-IR) spectroscopy and temperature programmed desorption (TPD) mass measurements. Modification of CsX with a small amount of FeCl3 could result in a considerable decrease in catalytic activity, due mainly to the remarkable decrease in the density of acidic and basic sites of the catalysts. Interestingly, the Fe(NO3)3-modified CsX with an optimum Fe loading of 0.15 wt.% shows improved catalytic activity and high yield compared to the side-chain alkylation products. Modification of CsX with Fe(NO3)3 could also result in a decrease in basic sites of the catalyst. However, such a change does not bring an obvious negative effect on the adsorption/activation of toluene, while it could effectively inhibit the generation of the undesired bidentate formate. Furthermore, the introduced FeOx species (derived from the decomposition of Fe(NO3)3) may also act as new Lewis acidic sites to participate in the activation of methanol and to stabilize the formed active intermediates (i.e., unidentate formate). Therefore, modification of CsX with a suitable amount of Fe(NO3)3 may adjust its adsorption/activation ability for reagents by changing the acid–base properties of the catalyst, which can finally enhance the catalytic performance for the side-chain alkylation of toluene with methanol.

Research of Catalytic Performance over Transition Metal Modified MnOx-CeOx/ACF Catalysts

2011 ◽  
Vol 383-390 ◽  
pp. 1945-1950 ◽  
Author(s):  
Bo Xiong Shen ◽  
Ting Liu ◽  
Ning Zhao ◽  
Juan Ma ◽  
Xiao Cui Hao
Keyword(s):  
Catalytic Activity ◽  
Thermal Treatment ◽  
Transition Metal ◽  
Catalytic Reduction ◽  
Surface Acidity ◽  
Catalytic Performance ◽  
Impregnation Method ◽  
Active Components ◽  
Scr Of No ◽  
Negative Effect

The catalyst of MnOx-CeOx/ACF prepared by impregnation method was used for low-temperature selective catalytic reduction (SCR) of NO with NH3, and more than 90% NO conversion was obtained at 230°C. Fe、Cu or V was used respectively to prepare transition metal modified MnOx-CeOx/ ACF catalysts which had lower catalytic activity than that over MnOx-CeOx/ACF. SEM, N2 adsorption and NH3-TPD were used to analyze the catalysts. The results showed that transition metal modified catalysts had a reduced surface area, pore volume and surface acidity. SO2 had a negative effect on SCR performance of the catalysts. Fe modified catalyst exhibited SO2 tolerance in the first 6h in the presence of 100ppm SO2. Thermal treatment in N2 at 350°C was used to regenerate the deactivated catalysts by SO2. The decomposition of ammonium salts recovered the catalytic activity to some extent. The sulfated active components in deactivated catalysts after the thermal treatment enhanced the surface acidity of the catalysts.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

scholarly journals Influence of the Reduction Temperature and the Nature of the Support on the Performance of Zirconia and Alumina-Supported Pt Catalysts for n-Dodecane Hydroisomerization

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 88
Author(s):  
Diana García-Pérez ◽  
Maria Consuelo Alvarez-Galvan ◽  
Jose M. Campos-Martin ◽  
Jose L. G. Fierro
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Catalytic Properties ◽  
Catalytic Performance ◽  
Major Influence ◽  
Pt Catalysts ◽  
Reduction Temperature ◽  
Metal Dispersion ◽  
Tungsten Oxides ◽  
Supported Pt Catalysts

Catalysts based on zirconia- and alumina-supported tungsten oxides (15 wt % W) with a small loading of platinum (0.3 wt % Pt) were selected to study the influence of the reduction temperature and the nature of the support on the hydroisomerization of n-dodecane. The reduction temperature has a major influence on metal dispersion, which impacts the catalytic activity. In addition, alumina and zirconia supports show different catalytic properties (mainly acid site strength and surface area), which play an important role in the conversion. The NH3-TPD profiles indicate that the acidity in alumina-based catalysts is clearly higher than that in their zirconia counterparts; this acidity can be attributed to a stronger interaction of the WOx species with alumina. The PtW/Al catalyst was found to exhibit the best catalytic performance for the hydroisomerization of n-dodecane based on its higher acidity, which was ascribed to its larger surface area relative to that of its zirconia counterparts. The selectivity for different hydrocarbons (C7–10, C11 and i-C12) was very similar for all the catalysts studied, with branched C12 hydrocarbons being the main products obtained (~80%). The temperature of 350 °C was clearly the best reduction temperature for all the catalysts studied in a trickled-bed-mode reactor.

scholarly journals A diffusion anisotropy descriptor links morphology effects of H-ZSM-5 zeolites to their catalytic cracking performance

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiaoliang Liu ◽  
Jing Shi ◽  
Guang Yang ◽  
Jian Zhou ◽  
Chuanming Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Cracking ◽  
Catalytic Performance ◽  
Zeolite Catalysts ◽  
Time Resolved ◽  
Cracking Performance ◽  
Morphology Effect ◽  
Ft Ir ◽  
The Difference ◽  
Dynamics Simulations

AbstractZeolite morphology is crucial in determining their catalytic activity, selectivity and stability, but quantitative descriptors of such a morphology effect are challenging to define. Here we introduce a descriptor that accounts for the morphology effect in the catalytic performances of H-ZSM-5 zeolite for C4 olefin catalytic cracking. A series of H-ZSM-5 zeolites with similar sheet-like morphology but different c-axis lengths were synthesized. We found that the catalytic activity and stability is improved in samples with longer c-axis. Combining time-resolved in-situ FT-IR spectroscopy with molecular dynamics simulations, we show that the difference in catalytic performance can be attributed to the anisotropy of the intracrystalline diffusive propensity of the olefins in different channels. Our descriptor offers mechanistic insight for the design of highly effective zeolite catalysts for olefin cracking.

scholarly journals Performance Analysis of TiO2-Modified Co/MgAl2O4 Catalyst for Dry Reforming of Methane in a Fixed Bed Reactor for Syngas (H2, CO) Production

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3347
Author(s):  
Arslan Mazhar ◽  
Asif Hussain Khoja ◽  
Abul Kalam Azad ◽  
Faisal Mushtaq ◽  
Salman Raza Naqvi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Fixed Bed Reactor ◽  
Dry Reforming Of Methane ◽  
Catalyst Stability ◽  
Feed Ratio ◽  
Catalyst Loading ◽  
Impregnation Method

Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process.

Three-dimensionally ordered macroporous spinel-type MCr2O4 (M = Co, Ni, Zn, Mn) catalysts with highly enhanced catalytic performance for soot combustion

2015 ◽  
Vol 5 (9) ◽  
pp. 4594-4601 ◽  
Author(s):  
Jinguo Wang ◽  
Gaoyang Yang ◽  
Li Cheng ◽  
Eun Woo Shin ◽  
Yong Men
Keyword(s):  
Catalytic Activity ◽  
Three Dimensional ◽  
Catalytic Performance ◽  
Soot Combustion ◽  
Spinel Type ◽  
Ordered Macroporous

MCr2O4 catalysts with three-dimensional ordered macroporous structures displayed superior catalytic activity for soot combustion to their bulk counterparts.

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

The use of catalyst to enhance the wet oxidation process

2007 ◽  
Vol 55 (12) ◽  
pp. 189-193 ◽  
Author(s):  
C. Maugans ◽  
B. Kumfer
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Acrylic Acid ◽  
Oxidation Process ◽  
Wet Oxidation ◽  
Test Results ◽  
Pure Compound ◽  
Spent Caustic

Wet oxidation tests were performed on two pure compound streams: acetic acid and ammonia; and on two wastewater streams: acrylic acid wastewater and sulphide laden spent caustic. Test results showed that Mn/Ce and Pt/TiO2 were effective catalysts that greatly enhanced acetic acid, ammonia and acrylic acid wastewater destruction. However, the Mn/Ce catalyst performance appears to be inhibited by concentrated salts dissolved in solution. This could limit the applicability of this catalyst for the treatment of brackish wastewaters. Zr, Ce and Ce nanoparticles were also shown to exhibit some catalytic activity, however not to the extent of the Mn/Ce and the Pt/TiO2.

The Synthesis of Iron Oxides with Different Phases or Exposure Crystal Planes and their Catalytic Property for Propene Oxidation

2012 ◽  
Vol 463-464 ◽  
pp. 189-193
Author(s):  
Kong Zhai Li ◽  
Masaaki Haneda ◽  
Masakuni Ozawa
Keyword(s):  
Catalytic Activity ◽  
Iron Oxides ◽  
Catalytic Property ◽  
Significant Influence ◽  
Catalytic Performance ◽  
Selective Growth ◽  
Crystal Plane ◽  
Low Density ◽  
Fe2o3 Nanoparticles ◽  
Propene Oxidation

Maghemite (γ-FeSubscript text2OSubscript text3) and hematite (α-Fe2O3) nanoparticles with various dominant exposure crystal planes were prepared by several different methods. The structure and the reducibility of these materials were investigated by XRD, Raman and H2-TPR technologies, and their catalytic performance for propene oxidation was also discussed. The maghemite (γ-FeSubscript text2OSubscript text3) showed a better reducibility than hematite (α-FeSubscript text2OSubscript text3), but its activity for propene oxidation is relatively lower. The exposure crystal plane of hematite has a significant influence on its catalytic activity for propene oxidation. Among the prepared four samples, the hematite-1 sample showed the best activity. The selective growth of any planes with a relative low density of Fe atoms for the α-FeSubscript text2OSubscript text3 catalyst would lead to an obvious decrease in the catalytic activity.

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