An efficient and environmentally friendly synthesis of AlFe-pillared clay (AlFe-PILC)-supported MnCe catalysts was explored. Mixed AlFe pillaring agents were prepared by a one-step method using Locron L and ferric nitrate solutions at a high temperature and high pressure. Montmorillonite was treated with the AlFe pillaring agents to synthesize AlFe-PILC. MnOx and CeO2 with different Mn/Ce atomic ratios were loaded onto the AlFe-PILC support by an impregnation method. The catalysts were characterized using X-ray diffraction, N2 adsorption, and high-resolution transmission electron microscopy–energy dispersive spectrometry and were tested for the catalytic combustion of benzene and temperature-programmed surface reaction using a microreactor. Compared to conventional methods, this method is simpler and less costly and results in a larger specific surface area, pore volume, and basal spacing, with the ability to control the structure of the catalytic materials. MnCe(6:1)/AlFe-PILC has the highest catalytic activity and can completely degrade benzene (600 ppm in air) at 250 °C. The activity of the catalyst is stable, and no obvious deactivation is observed at 230 °C after 1000 continuous hours. The catalyst is resistant to water and Cl-poisoning. The amount of CeO2 added is critical to the dispersion of MnOx on the support and the creation of optimum number of oxygen vacancy defect sites for the benzene oxidation reaction. The AlFe-PILC-supported MnCe catalyst is a promising porous material; the support structure, proper dispersion of active species, and addition of Ce are essential for achieving complete degradation of organic toxic chemicals at relatively low temperatures.Topics: Catalysts; Powder x-ray diffraction; Surface reaction;

•Addition of Ce and Pt promoted the oxidative performance of V2O5/γ-Al2O3.•Redox properties were enhanced due to the Pt-Ce-V interaction.•0.3%Pt/10%Ce-10%V/γ-Al2O3 displayed good durability and resistance to Cl-poisoning.In the present work, a commercial mesoporous γ-Al2O3 with large specific surface area, high mechanical strength and good thermal stability was employed as the support for preparing a series of V2O5/γ-Al2O3 materials with different loading amounts of V2O5. Ce and Pt were introduced in order to further promote the oxidative performances for catalytic combustion of benzene, a typical pollutant of various volatile organic compounds (VOCs) in industrial waste gases. To investigate the structure − catalytic property relationship, these catalytic materials were systematically characterized by the XRD, N2 adsorption/desorption, HRTEM, EDX, H2-TPR and in-situ TPSR techniques. The results showed that the introduction of 10%wt Ce and 0.3%wt Pt significantly improved the catalytic oxidative activity and CO2 selectivity of the V2O5/γ-Al2O3 catalysts for benzene combustion, due to the obvious enhanced redox property resulted from the metal–metal and metal-support interaction as well as the high dispersion of the active components on γ-Al2O3. Furthermore, the 0.3%Pt/10%Ce-10%V/γ-Al2O3 catalyst also represented good durability and resistance to water and Cl-poisoning during the long-time continuous reaction, implying that it deserved more attention and had good potential for industrial application.Download high-res image (530KB)Download full-size image

A new type of porous kaolin/NaY composite (KL-NY) with a large specific surface area and large pore sizes was synthesized through a one-step crystallization process, and rare earth-modified KL-NY-supported Pd–Pt catalysts were studied for benzene combustion. The results indicated that the pore volume and specific surface area of KL-NY after calcination and crystallization were 0.298 cm3/g and 365 m2/g, respectively, exhibiting appropriate pore structure and good thermal stability. Catalysts with rare earth metals greatly enhanced the activity of Pd/KL-NY, and the addition of Pt and Ce into the Pd catalyst improved the catalytic activity as well as the stability. The catalyst with an optimal Ce content and Pt/Pd molar ratio (0.2%Pd–Pt (6:1)/6%Ce/KL-NY) demonstrated the best activity for the complete oxidation of benzene at 230 °C, and the catalyst above maintained the 100% benzene conversion for 960 h.Keywords: catalytic combustion; kaolin/NaY; Pd−Pt; rare earth; volatile organic compounds

•Nanosized MCM-41 with large SBET and Vp was prepared.•Highly dispersed Pt oxide catalyst doping with neodymia on MCM-41 was prepared.•High activity is related to improved structure and dispersed active sites.•0.2%Pt/6%Nd/MCM-41 exhibits highest activity and stability for benzene combustion.A series of rare earth elements (REE)-modified Pt/MCM-41 catalysts were prepared. The effects of REE-doped MCM-41 on the performance of 0.2%Pt/MCM-41 and on benzene combustion were evaluated. XRD spectra and N2 adsorption show MCM-41 with high specific surface area and large pore volume has a highly ordered hexagonal mesostructure. The UV–vis DRS show that size of Pt particles changes in the trend of small size after adding Nd, and this result is in excellent agreement with the data obtained from HRTEM-EDS. The highest catalytic activity and durability of 0.2%Pt/6%Nd/MCM-41 is attributed to an optimized Nd content, Pt particles with smaller size and high Pt dispersion on MCM-41.Download high-res image (333KB)Download full-size image

•NaY-type zeolite crystal (KL-NY) with large SBET and Vp was prepared as support.•Highly dispersed MnOx and CeO2 modified KL-NY catalysts was prepared.•High activity is related to improved structure and highly dispersed active sites.•10%MnCe(9:1)/KL-NY exhibits the highest activity and stability for benzene oxidation.In this paper, a new kaolin-based NaY-type zeolite crystal (KL-NY) material was synthesized through in-situ crystallization, and CeO2-modified KL-NY-supported manganese oxide catalysts (MnCeOx/KL-NY) were further prepared and investigated for benzene combustion. The texture-structure, surface morphology, dispersion of active components and the redox properties of the materials were systematically characterized and analyzed by the techniques of N2 adsorption-desorption, high resolution transmission electron microscopy (HRTEM)-energy dispersive spectroscopy (EDS) as well as the H2 temperature-programmed reduction (H2-TPR). The results showed that the calcinated and crystallized KL-NY support exhibited good thermal stability with large specific surface area and large pore volume. The MnCe/KL-NY catalysts exhibited excellent deep oxidation properties. Among them, 10%MnCe(9:1)/KL-NY displayed the highest catalytic activity and could completely oxidize low-concentration benzene at 260 °C; its activity did not decrease after continuous reaction for 800 h, indicating its high potential for industrial application. The improved catalytic properties of the MnCe/KL-NY catalysts were mainly related to the higher oxidation state of MnOx and the preferable redox properties, resulted from the highly dispersion of CeO2 and MnOx on the surface of KL-NY as well as their strong interaction.Download high-res image (205KB)Download full-size image