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A series of cerium phosphate catalysts with different crystal phases were synthesized by hydrothermal method and co-precipitation method. Hexagonal cerium phosphate (CePO4-H) shows better NH3-SCR denitration activity than monoclinic cerium phosphate (CePO4-M) and mixed phases of CePO4-H and CePO4-M. Moreover, CePO4-H also exhibits excellent activity stability with stream time and cycle used stability. Various characterizations were carried out to explain the effects of different crystal phases of CePO4 on the activity. Among these catalysts, CePO4-H has much stronger surface acidity that is conducive to the adsorption and activation of NH3, and more surface adsorbed oxygen species that can effectively improve SCR activity. In situ DRIFTS were performed to investigate the adsorption and reaction of NH3 and NOx on CePO4-H and CePO4-M, and the results suggest that the better activity over CePO4-H follows mainly the E-R mechanism in the activity temperature window (300–500 oC) with 100% NO conversion.

The formation of K–O–Mn bond weaken the bond of Mn–O–Mn which increases oxygen species mobility leading to excellent catalytic oxidation performance over OMS-2 by introducing different amounts of K.

It is highly desirable but quite challenging to replace precious metals with cheaper elements in the catalytic selective hydrogenation of unsaturated aldehydes. Herein, we report the preparation of a series of CuxNi3-xAlOy mixed-metal oxides (x = 0.5, 1, 2) derived from CuxNi3-xAl hydrotalcite to be used as catalysts for the promotion of the selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL). It was found that the catalyst with the Cu2Ni1AlOy stoichiometry exhibited the best performance, with 98% FAL conversion and 99% selectivity toward FOL after 1.5 h at 120 °C and under a H2 pressure of 1.6 MPa, and also good reusability. On the basis of the combined results from catalyst characterization studies using XRD, H2-TPR, TEM, XPS, and in-situ FT-IR, it was concluded that the CuOx species on the surface of the CuxNi3-xAlOy catalysts can be reduced in situ to metallic copper during reaction, and that this Cu0 species is likely the responsible for the adsorption and conversion of FAL. The addition of Ni to these mixed-metal oxides helps disperse the Cu phase and hence make it easier to reduce and activate. It may also be that NiO can promote H2 dissociation to aid with the hydrogenation catalysis. Our work advances a new strategy for the design of simple, cheap, and efficient catalysts for the hydrogenation of FAL to FOL.

Catalytic oxidation is considered a high-efficient method to minimize efficiently toluene emission. It is still a challenge to improve the catalytic performance for toluene oxidation by modifying the surface properties to enhance the oxidation ability of catalyst. Herein, a series of CuaCo1−aOx (a = 0.1, 0.2, 0.4, 0.6) catalysts were synthesized via solvothermal method and applied for toluene oxidation. The effects of the Cu/Co ratio on the texture structure, morphology, redox property and surface properties were investigated by various characterization technologies. The Cu0.4Co0.6Ox catalyst with dumbbell-shaped flower structure exhibited much lower temperature of 50% and 100% toluene conversion and far higher reaction rate (13.96 × 10−2 μmol·g−1·s−1) at 220 °C than the Co based oxides in previous reports. It is found that the good activity can be attributed to the fact that the proper Cu/Co ratio can significantly improve the formation of more surface adsorbed oxygen and Co3+ species, leading to the much higher oxidation ability came from the strong interaction between Cu and Co oxides. It is suggested that toluene should be oxidized more rapidly to CO2 and H2O over the Cu0.4Co0.6Ox catalyst than Co3O4 based on the results of in situ DRIFTS.

Catalytic oxidation is regarded as an effective, economical, and practical approach to remove volatile organic compounds such as important air pollutants. CeO2 catalysts with different morphologies exhibit different oxygen vacancies content, which plays a vital role in oxidation reaction. Herein, three distinct morphologies of CeO2 i.e., shuttle (CeO2 (S)), nanorod (CeO2 (R)), and nanoparticle (CeO2 (P)), were successfully fabricated by the SEM and TEM results, and investigated for toluene catalytic oxidation. The various characterizations showed that the CeO2 (S) catalyst exhibited a larger surface area along with higher surface oxygen vacancies in contrast to CeO2 (R) and CeO2 (P), which is responsible for its excellent toluene catalytic oxidation. The 90% toluene conversion temperature at 225 °C over CeO2 (S) was less than that over CeO2 (R) (283 °C) and CeO2 (P) (360 °C). In addition, CeO2 (S) showed a greater reaction rate (14.37 × 10−2 μmol∙g−1∙s−1), TOFov (4.8 × 10−4∙s−1) at 190 °C and lower activation energy value (67.4 kJ/mol). Furthermore, the CeO2 (S) also displayed good recyclability, long-term activity stability, and good tolerance to water. As a result, CeO2 (S) is considered a good candidate to remove toluene.

Catalytic oxidation is considered as the most effective and economical method to remove low concentration volatile organic compounds (VOCs). Activation of oxygen to form active oxygen species on metal oxides catalyst plays a key role in the process. Three copper-manganese oxide catalysts with cubic Cu

The Pt/(Fe, Mn/Co)-BTC catalysts were fabricated by a facile ultrasonic impregnation assisted hydrothermal polyol reduction method using first MIL-100(Fe, Mn/Co) MOFs as supports and tested for selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL). Various characterizations including XRD, TG, FT-IR, N2 physical adsorption, ICP-OES, SEM, TEM and XPS were applied for exploring structure changes and surface properties of the catalysts. Over 98% conversion of FAL and 99% selectivity to FOL were achieved over Pt/(Fe, Mn)-BTC and Pt/(Fe, Co)-BTC, moreover, Pt/(Fe, Co)-BTC showed higher turnover frequency (TOF) of 1,044 h−1 and better cycle stability, which are better than other catalysts prepared by using H2, NaBH4, and formaldehyde as reductants. Overall, the formation of highly dispersed small-sized Pt NPs (about 1.7 nm) with much higher content of surface Pt0 on the catalysts is the key of excellent hydrogenation activity due to the strong interaction between Pt NPs and the bimetallic supports.

Precious metals have been shown to play a vital role in the selective hydrogenation of α,β-unsaturated aldehydes, but still suffer from challenges to control selectivity. Herein, we have advanced the design of catalysts made out of Pt–Co intermetallic nanoparticles (IMNs) supported on a MIL-101(Cr) MOF (3%Pty%Co/MIL-101(Cr)), prepared by using a polyol reduction method, as an effective approach to enhance selectivity toward the production of α,β-unsaturated alcohol, the desired product. XRD, N2 adsorption–desorption, FTIR spectroscopy, SEM, TEM, XPS, CO adsorption, NH3-TPD, XANES and EXAFS measurements were used to investigate the structure and surface properties of our 3%Pty%Co/MIL-101(Cr) catalysts. It was found that the Co-modified 3%Pty%Co/MIL-101(Cr) catalysts can indeed improve the hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL), reaching a higher selectivity under mild conditions than the monometallic Pt/MIL-101(Cr) catalysts: 95% conversion of CAL with 91% selectivity to COL can be reached with 3%Pt3%Co/MIL-101(Cr). Additionally, high conversion of furfural (97%) along with high selectivity to furfural alcohol (94%) was also attained with the 3%Pt3%Co/MIL-101(Cr) catalyst. The enhanced activity and selectivity toward the unsaturated alcohols are attributed to the electronic and geometric effects derived from the partial charge transfer between Co and Pt through the formation of uniformly dispersed Pt–Co IMNs. Moreover, various characterization results revealed that the addition of Co to the IMPs can promote the Lewis acid sites that facilitate the polarization of the charge-rich CO bonds and their adsorption via their oxygen atom, and also generate new interfacial acid sites.

The addition of a suitable co-catalyst is an encouraging way to enhance the catalytic performance of Pd based catalyst with low content. Herein, we describe an easy synthesis of Mo2N-TiO2 with well-dispersed Mo2N nanoparticles through one pot evaporation-induced self-assembly and nitridation treatment method. Moreover, a green bio-reductive approach with Catalpa Fruit (CF) extract was adopted to fabricate Pd/Mo2N-TiO2 catalysts for promoting selective hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as model reaction. Among these Pd/Mo2N-TiO2 catalysts, 0.8 wt%Pd/Mo2N-TiO2 exhibits significantly high catalytic activity for selective hydrogenation of various nitrophenols and cinnmaldehyde. Importantly, the catalytic activity of the catalyst prepared by the reduction method of the CF extract is higher than that prepared by the reduction method of NaBH4. A serials of characterization, including XRD, N2 adsorption–desorption, TEM, XPS, CO chemisorption and CO-FTIR etc., was carried out to investigate the influence of the prepared method on the surface Pd species and activity. The high performance can be attributed to the specific nanostructure characteristics of the catalyst and the good synergistic effect between Pd and Mo2N, improving the dispersion of Pd nanoparticles atoms and the exposure of more active Pd atoms (surface Pd0 species) on 0.8 wt%Pd/Mo2N-TiO2 due to the CF extract as reductant.

The adsorption and delivery of reactants to active sites are the first two steps of catalytic reactions, however, which receive less attention compared with the design of highly active sites. Herein, we provide an improvement of the two crucial steps by designing perovskite oxides-carbon composites (LaFeO3_N) for catalytic transfer hydrogenation (CTH) of furfural to furfuryl alcohol. The principle is to ensure that the reactants can be timely supplied to the active sites for reaction. Indeed, the reaction rate over LaFeO3_N increases tremendously to 5.17 mmol g−1 h−1 that is 6 times higher than that over LaFeO3_A (0.81 mmol g−1 h−1) without carbon material. The results suggest that LaFeO3_N can improve the migration of reactants from solution to LaFeO3 active sites due to the presence of carbon, which has the ability to absorb and deliver the reactants. Effects of carbon content and carbon texture on the reaction are fully investigated. The current strategy of improving the catalytic performances of perovskite oxides can be easily applied to other catalytic systems with low surface area.

MoaMnTi10Ox (a= 0.2, 0.4, 0.6 and 0.8) catalysts have been prepared by sol-gel and applied in the NH3-SCR of NO reaction. These catalysts were characterized by XRD, H2-TPR, NH3-TPD, XPS and in situ DRIFTS. Among the MoaMnTi10Ox catalysts, Mo0.6MnTi10Ox exhibits the excellent NH3-SCR performance with a broaden activity temperature window even in presence of 5 vol.% H2O, together with an excellent resistance of H2O and SO2. Compared with MnTi10Ox, the Mo addition leads to the reduction of redox ability, improvement of the surface acid sites and inhibition of NO adsorption. A serial of characterizations confirms that the synergistic effect between redox property and surface acidity plays a key role in the much better NH3-SCR activity over Mo0.6MnTi10Ox. Furthermore, the in situ DRIFTS studies reveal the NH3-SCR reaction is following the E-R mechanism over Mo0.6MnTi10Ox at 210 °C. In addition, the effects of H2O on the NH3-SCR reaction are investigated by in situ DRIFTS.

To save time and economic cost of the synthesis of SAPO-34 zeolites, the effects of hydrothermal time on the structure and methanol-to-olefin (MTO) catalytic activity of SAPO-34 zeolites were investigated in detail. A series of SAPO-34 zeolites (SAPO-34-x h, x = 3, 4, 8, 12, 24 and 48) were obtained using the traditional hydrothermal method by changing the synthesis time at 210 °C. The obtained catalysts were characterized by XRD, N2 adsorption–desorption, SEM, TG-DTA, ICP, 29Si and 27Al MAS NMR and NH3-TPD techniques. Among these samples, SAPO-34-4 h with a higher Si/(Si + Al + P) ratio shows a much longer lifetime (518 min) and higher light olefin selectivity (82.0%) in the MTO reaction, which can be attributed to the unique Si distribution and low acidity. Moreover, the SAPO-34-4 h sample can maintain good MTO performance even under long time storage without complicated processing or after several cycles of regeneration. This facile synthesis procedure may be beneficial for large scale industrial catalyst production because of its short synthesis time.

Hydrogen is the most desirable green energy carrier and electrocatalytic hydrogen evolution reaction (HER) from water is a promising route for hydrogen production. The search for efficient, low-cost HER catalysts is a challenging and attracting topic. In this work, we report that inorganic fullerene-like WS2 supported Pd nanoparticles (Pd/WS2), with Pd loading of 0.76 wt%, are active for electrocatalytic HER conducted in 0.5 M H2SO4 solution, with overpotential at 10 mA cm−2 current density of ~130 mV and Tafel slope of 82.4 mV dec−1, which is comparable to that of Pt/WS2 (0.88 wt% Pt loading) with higher costs. Characteristic results indicate that WO3 impurities were in-situ produced on the WS2 surface and the Pd NPs are primarily located inside the WS2 nanocages. Contrasting experiments suggest that the WO3 impurities play a crucial role in generating Hads intermediate and the Pd NPs are active sites of H2 production, and a reaction mechanism is proposed. The Pd/WS2 catalyst also shows good long-term stability owing to the location of Pd NPs inside the WS2 cages. The high HER activity, low costs and good stability make the Pd catalyst a potential alternative to Pt catalyst for HER.

This work presents a novel and highly efficient NH

A series of tungsten-modified Cu0.02Fe0.2TiOx catalysts (Cu0.02Fe0.2WaTiOx; a = 0.01, 0.02, and 0.03) was synthesized by sol-gel method. Their catalytic activities were investigated for the selective catalytic reduction (SCR) of NO with NH3, in the presence/absence of 5 vol.% H2O. The characterization techniques of XRD, BET, Raman, H2-TPR, NH3-TPD, XPS, in situ DRIFTS, and kinetic studies were used to reveal the effect of tungsten modification on the redox and acidity of the Cu0.02Fe0.2WaTiOx catalysts. The relationship among the species composition, acid property, and oxidation-reduction behavior of the Cu0.02Fe0.2WaTiOx catalysts was established. Results demonstrated that a moderate amount of tungsten doping can markedly enhance the specific surface area, improve the abundant Bronsted and Lewis acid sites, and tune the surface species composition, which all benefited high-performance catalysis. Water/sulfur resistance also improved because of the excellent acidity levels. Among the Cu0.02Fe0.2WaTiOx catalysts, Cu0.02Fe0.2W0.02TiOx showed the highest NO conversion, a wide reaction-temperature window (235–520 °C) with >90% NO conversion, high N2 selectivity, and high water/sulfur resistance even in the presence of 5 vol.% H2O. Moreover, Cu0.02Fe0.2W0.02TiOx retained its outstanding catalytic activity under a rather high gas hourly space velocity (GHSV) of 100,000 h−1. In conclusion, the combined effects of redox and sufficient acidities on catalytic activity played key roles in superior SCR performance and water/sulfur durability. Furthermore, the NH3-SCR reaction over Cu0.02Fe0.2W0.02TiOx may follow the Eley–Rideal reaction pathway according to the in situ DRIFTS and kinetic studies results.

The design of a stable and efficient catalyst is crucial to the creation of high-valued bio-based products, and the catalytic selective oxidation of 5-hydroxymethylfurfural (5-HMF) to 2, 5-furandicarboxylic acid (FDCA) has received increasing attention. Different loadings of Au supported on the graphitized carbon (GC) catalysts (xwt%Au/GC (x = 0.7, 1.0, 1.3, 2.0 and 2.7)) were prepared and characterized via ICP-OES, N2 adsorption-desorption, XRD, FT-IR, TG, XPS and TEM. Results show that 2.0 wt%Au/GC displays 97% selectivity of FDCA and a near 100% conversion of 5-HMF in water under 7 bar O2 pressure for 6 h at 110 °C in the presence of NaOH, which also exhibits good cycling stability. The surface species of Au0 are in favor of the formation of FDCA. In this work, different reaction parameters were explored to optimize the reaction condition. The intermediates and the reaction pathways were also proposed on the basis of the formation and degradation of esters via various characterizations.

A series of CeaMnOx hollow microsphere like arbutus with hierarchical structure are prepared by redox co-precipitation method and applied for catalytic toluene combustion. The Ce0.03MnOx shows a better catalytic performance for toluene combustion with high stability, water resistance, even under the condition of 5vol.% H2O. The results of XRF, XRD, Raman, N2 adsorption-desorption, SEM, TEM prove that the doping of Ce can affect the structure of CeaMnOx such as much smaller particle size and higher specific surface area. The characterizations of H2-TPR, O2-TPD, XPS certify the strong interaction between Ce and Mn oxides that leads to more surface adsorbed oxygen and Mn4+ species due to oxidation reduction cycle of Mn3+ + Ce4+ ↔ Mn4+ + Ce3+ after Ce addition. Meanwhile, the Toluene-TPD in different conditions confirms the introduction of water promoted the catalytic oxidation of toluene. In situ DRIFTS is used to investigate the reaction process of toluene oxidation. And the results reveal that the Ce0.03MnOx catalyst has much stronger ability to adsorb and activate toluene compared with MnOx catalyst, especially under with H2O. That may be the main reason that the Ce0.03MnOx catalyst exhibits the special catalytic activity for toluene combustion.

Catalytic transfer hydrogenation is an attractive route for the synthesis of biomass-derived chemicals. However, development of efficient, low-cost, and stable catalysts for that reaction is still a challenge. Here, we report on the preparation and testing of a non-noble perovskite oxide (LaFeO3) catalyst synthesized by an in situ carbon templating method. We show that our catalyst is quite active and selective toward the hydrogenation of unsaturated organics. Compared to an analogous LaFeO3 catalyst prepared by a more traditional method, using citric acid, the new LaFeO3 exhibited a more porous structure, a La-enriched surface composition, and abundant oxygen vacancies, all characteristics that improve contact with the reactants. In the case of the conversion of furfural to furfuryl alcohol (FOL) using iso-propanol as hydrogen donor, the new LaFeO3 showed a furfural conversion of 90% and a selectivity to FOL of 94%, significantly higher than with the reference LaFeO3 prepared by the traditional sol-gel method (60 and 91%, respectively). Moreover, our new LaFeO3 catalyst can be recovered after a calcination treatment, with no appreciable changes in its structure or activity, a test that we repeated six times, and can promote the hydrogenation of other carbonyl compounds containing electron-withdrawing groups. A reaction mechanism is proposed in which metal cations are the adsorption sites for iso-propanol and oxygen vacancies are the adsorption sites for furfural, and where the conversion proceeds following an acid-base mechanism. We believe that the novel use of perovskites as catalysts for hydrogenation reactions reported here may be easily extendable to other processes, and that our carbon-templating synthetic approach offers a way to synthesize viable perovskite catalysts with high surface areas for optimized activity.

SAPO-34 with a sub-micrometer crystal size was synthesized by a double hydrothermal treatment employing cost-effective morpholine as a structure directing agent, which presented an enhanced catalytic lifetime (nearly 3 times the conventional one) in the reaction of methanol to olefins with a higher light olefin selectivity (total selectivity of 97.1%). Detailed studies of the sample after different time intervals in the second crystallization with and without additional morpholine were carried out, which offered insight into crystal degradation and re-crystallization phenomena. The samples with different morpholine concentrations during the second hydrothermal treatment were also prepared, in which the sample with 80% MOR aqueous solution exhibited the smallest crystal size and the longest MTO lifetime. Furthermore, the investigation on the additional amount of mother liquor (from the first crystallization) required for the second crystallization showed that the presence of half the amount of the mother liquor (nutrients) could give us the required results effectively.

A series of Ce0.1TiOx, Cu0.1Ox and CumCe0.1-mTiOx (m = 0.01, 0.02, 0.03) catalysts are prepared via a sol-gel method for the selective catalytic reduction (SCR) of NO with NH3. The samples are mainly characterized by X-ray diffraction (XRD), Raman, H2-TPR, NH3-TPD, separated NO/NH3 oxidation, X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to investigate the properties of the catalysts. Among the CumCe0.1-mTiOx (m = 0.01, 0.02, 0.03) catalysts, Cu0.01Ce0.09TiOx displays much better catalytic activity in the range of 170 °C–425 °C (> 90% NO conversion), N2 selectivity and resistance of SO2 and H2O even at high gas hourly space velocity. The XPS results verify that the introduction of Cu leads to a copper species enrichment environment and the formation of more surface Ce3+ and absorbed oxygen (Oα), which are in favor of the oxidation of NO to NO2, enhancing the activity at low temperature. Furthermore, in situ DRIFTS results confirm that the Langmuir-Hinshelwood (L-H) mechanism is predominant in the NH3-SCR process for the Cu0.01Ce0.09TiOx catalyst at 150 °C.

Citric acid method was employed to prepare a series of Nb-promoted Fex-Nb0.5-x-Ce0.5 (x = 0.45, 0.4, 0.35) oxides for selective catalytic reduction with NH3 (NH3-SCR) of NO process. The structure, redox ability and reactivity of NH3 and absorbed NO species on the catalysts were explored by using various characterization techniques such as X-ray diffraction (XRD), temperature program reduction with H2 (H2-TPR), temperature program desorption of NH3 (NH3-TPD), temperature program desorption of NO (NO-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). It was found that the Nb promoted Fex-Nb0.5-x-Ce0.5 (x = 0.45, 0.4, 0.35) oxides catalysts showed outstanding NH3-SCR of NO activity, excellent N2 selectivity and remarkable SO2/H2O resistance, meanwhile, Fe0.4-Nb0.1-Ce0.5 exhibited above 90% NO conversion in the range of 180–400 °C, together with near 100% N2 selectivity. The characterization results point out that the excellent catalytic performance of Fe0.4-Nb0.1-Ce0.5 can be ascribed to the strong interaction among Nb, Fe and Ce oxides. The strong interaction not only increases the BET surface area and redox ability of the catalyst, but also significantly improves the acid amount leading to the enhancement of the adsorption and activation of NH3, which is advantage of the reactivity of adsorbed nitrate together with the adsorbed NH3 species.

A series of Co0.2CexMn0.8-xTi10 (x = 0, 0.05, 0.15, 0.25, 0.35 and 0.40) oxides catalysts were prepared by the sol-gel method and used for NH3-SCR. These catalysts were characterized by means of XRD, SEM-EDS, H2-TPR, NO/NH3 oxidation, NH3 (NO and SO2)-TPD, XPS and in situ DRIFTS. It was found that the Co0.2Ce0.35Mn0.45Ti10 catalyst showed excellent NH3-SCR activity and a broaden temperature window (180–390 °C), accompanied with good resistance to SO2 and H2O. It could be concluded that the redox ability of Co0.2Ce0.35Mn0.45Ti10 could be reduced by Co and Ce doping, which resulted in high NH3-SCR activity at high temperature and good resistance of SO2. The addition of Co and Ce can supply more acid sites and NOx adsorption sites over Co0.2Ce0.35Mn0.45Ti10. Thus, more surface Bronsted acid and Lewis acid sites, NOx adsorption sites and modest redox ability of Co0.2Ce0.35Mn0.45Ti10 play key roles in the special NH3-SCR activity due to the interactions among Ce, Co, Mn and Ti oxides. Furthermore, the results of in situ DRIFTS study reveal the NH3-SCR reactions over Co0.2Ce0.35Mn0.45Ti10 and Co0.2Mn0.8Ti10 catalysts are mainly controlled by E-R mechanism (>210 °C) and the L-H mechanism (

A convenient sol-gel method was used to prepare a series of MnaCe0.3TiOx (a = 0.1, 0.2, 0.3) catalysts and applied in selective catalytic reduction with NH3 (NH3-SCR) for NO removal. XRD, BET, Raman, H2-TPR, NH3-TPD, SO2-TPD, XPS and in situ DRIFTS were applied to analyze the texture structure, redox property, acidity and surface properties. The Mn0.1Ce0.3TiOx catalyst exhibited a dramatical performance that 100% NO conversion and above 90% N2 selectivity were obtained between 175 and 400 °C, even under high gas hourly space velocity of 80,000 h−1 and existence of SO2 and H2O. The results can be attributed to that Mn0.1Ce0.3TiOx catalyst possessed the most chemisorbed oxygen and suitable redox property derived from Ce3+ + Mn4+ ↔ Ce4+ + Mn3+ reaction. In situ DRIFTS revealed that the NH3-SCR reaction upon Mn0.1Ce0.3TiOx catalyst took place by L-H and E-R mechanisms below 175 °C while only E-R mechanism above 175 °C.

Coral-like lanthanum manganese oxides (LayMnOx) with a hierarchical structure nanosphere were successfully prepared using a simple method, which presented a high-efficiency catalytic performance for toluene combustion. Among them, La0.08MnOx with the Mn3O4 phase exhibits superior catalytic activity, such as a lower T95 value (218 °C), excellent H2O resistance, and catalytic stability. The effects of La addition on the bulk and surface physicochemical properties of LayMnOx were investigated by sorts of characterization including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption, temperature-programmed reduction with H2, temperature-programmed desorption of O2, X-ray photoelectron spectroscopy, and so forth. The results demonstrate that the doping of La can induce the variation of physicochemical properties and the formation of more surface oxygen species and high valence state amorphous manganese oxides, improving low-temperature reducibility, which facilitates good catalytic activity for La0.08MnOx. A series of in situ diffuse reflectance infrared Fourier transform spectroscopy experiments for toluene adsorption were performed on the La0.08MnOx catalyst pretreated under different atmosphere conditions to investigate the role of oxygen species and the reaction processes. The results indicate that the abundant surface oxygen species over La0.08MnOx can make the rapid formation of benzoic acid species, further transfer into CO2 and H2O, which is considered as the key factor in the activation and oxidation of toluene.

The Cux-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) bimetal oxides catalysts were synthesized through citric acid method and used in the selective catalytic reduction (SCR) of NO with NH3. The relationship among the catalytic performances, the acid/redox properties and the structures of the binary oxides systems was explored through different characterization techniques including XRD, H2-TPR, BET, NO-TPD, NH3-TPD, XPS and in situ DRIFTS. The characterization results point out that the ratio of Cu to Nb has great influence on the activity of NH3-SCR reaction. Different catalytic activities of Cux-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) mixed oxides could be attributed mainly to surface area, acid amount, the adsorption and activation of NH3 and redox ability of the corresponding catalyst. Among these Cux-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) oxides catalysts, the Cu0.25-Nb0.85 catalyst exhibited the complete NO conversion in a reaction temperature range of 180-330 °C, together with near 100% N2 selectivity and remarkable SO2/H2O resistance. Moreover, the Cu0.25-Nb0.85 catalyst still exhibited wide activity temperature window of 185-380 °C at above 90% NO conversion even in the presence of 5% H2O under high GHSV of 70,000 h-1. Thus, it can be summarized from the above results that Cu0.25-Nb0.85 can be considered as excellent catalyst for NH3-SCR of NO.

A facile way to synthesize a series of SAPO-34 zeolites was developed by using the mixed templates of morpholine and TEAOH with changing the temperature. Among these samples, SAPO-34-210 exhibited with the longest lifetime and the highest selectivity to light olefin for methanol to olefin (MTO) reaction. The characterizations suggested that SAPO-34-210 has unique Si distribution due to much more amount of TEAOH introduced into structure, which resulted in the excellent catalytic performance.

The selective synthesis of SAPO-5, SAPO-5/SAPO-34 mixture and SAPO-34 was performed by increasing Si/Al ratio and pH through hydrothermal synthesis route, in which the product was successively switched from AFI to AFI/CHA and to CHA. The samples were characterized by XRD, XRF, SEM, and NH3-TPD techniques. It indicates that the SAPO-5/SAPO-34 mixture exhibits higher acidity than the pure SAPO-5 and SAPO-34 phases. During methanol-to-olefins reaction, the catalytic lifetime of the SAPO-5/SAPO-34 mixture was significantly longer than that of SAPO-34, which may be attributed to the moderate acidity of the SAPO-5/SAPO-34 mixture.

A series of NbmCu0.1-mCe0.9Ox catalysts were synthesized with the help of citric acid method, and used for the selective catalytic reduction of NOx with NH3 (NH3-SCR). The catalytic performance of the NbmCu0.1-mCe0.9Ox samples was greatly improved after the introducing of niobium. Among all catalysts, the Nb0.06Cu0.04Ce0.9Ox catalyst revealed the best low-temperature SCR activity, higher N2 selectivity and extraordinary SO2 and H2O durability with 100% NO conversion at 150–390 °C. The various characterization techniques were carried out to investigate the effect of niobium doping on the physical structures, surface properties and NH3-SCR activity of catalysts. Results reveal that the oxidation ability decrease but the acidity is enhanced with the Nb addition. The improved acidity by niobium doping is considered the primary cause for the superior deNOx performance of the Nb0.06Cu0.04Ce0.9Ox catalyst at low temperature, which can offset the negative effects of the reduced oxidation ability on activity. Furthermore, in situ DRIFTS results were applied for the investigation of the reaction process in detail.

OMS-2 with the hierarchical pore structure (OMS-2-OA) was successfully synthesized by etching with H2C2O4 and applied for catalytic toluene oxidation. A series of characterizations (including XRD, SEM, TEM, N2 adsorption-desorption, O2-TPD and so on) were performed to explore the relation between the activity and properties of OMS-2-OA. The results confirm the formation of mesopore on the OMS-2-OA after etching with H2C2O4, but it still maintains the cryptomelane structure and nano-rod morphology of OMS-2. Compared with OMS-2, OMS-2-OA shows the better catalytic toluene oxidation performance that the temperatures of 50% and 100% toluene conversion get to 212 and 225 °C, respectively, which can be attributed to the more amount of K+ and Mn4+ on OMS-2-OA than those on OMS-2, enhancing its lattice oxygen activity and oxidation ability. Moreover, a small amount of H2O addition in the feed can improve the catalytic performance and stability of OMS-2 and OMS-2-OA. In addition, a series of OMS-2-OA samples after long-term use were treated at different reaction conditions and characterized to investigate the factors in affecting catalytic activity for OMS-2-OA. This work provides a method to change surface chemical environment and form mesopore structure of MnOx to tune its catalytic activity by etching with H2C2O4.

A low hydrothermal temperature, short crystallization time and green strategy is developed for the synthesis of low-silica SAPO-34. The samples were prepared by adjusting the additional pressure with N2 using TEA as the sole template. The pure SAPO-34 (SP-C4) was obtained only under pressure of 2.7 MPa which possessed the smaller crystal size and moderate acidity and showed enhanced the lifetime and light olefins selectivity in methanol to olefins. And the possible formation mechanism of low-silica SAPO-34 was proposed.

A series of Cux-Ce0.5-x-Zr0.5 oxides catalysts with different Cu/Ce ratio were synthesized by citric acid method. The catalysts were characterized by XRD, BET surface area, H2-TPR, NH3-TPD, NO-TPD, XPS and in-situ DRIFTS. The synergistic effect between copper and cerium on the catalytic performance of Cux-Ce0.5-x-Zr0.5 for selective catalytic reduction of NO with ammonia was investigated. It was found that the Cu0.2-Ce0.3-Zr0.5 catalyst show the excellent SCR activity, N2 selectivity and H2O/SO2 durability in a low temperature range of 150–270 °C even at high gas hourly space velocity of 84,000 h−1. The strong interaction leads to the improvement of the acidity and the increase in the amount of active oxygen species (oxygen vacancy), which are responsible for the higher activity at low temperatures. The SCR reaction process over Cu0.2-Ce0.3-Zr0.5 was also examined using in-situ DRIFTS. The DRIFTS results indicate that abundant ionic NH4+ (Bronsted acid sites), coordinated NH3 on the Lewis acid sites, as well as highly active monodentate nitrate and bridging nitrate species were the key intermediates in the SCR reaction.

In this paper, the activity of La1.6Ba0.4NiO4 (LBN) and Ru/La1.6Ba0.4NiO4 (Ru/LBN) perovskite-like catalysts was investigated for NO + CO reaction. Meanwhile, Ru/LBN exhibited much higher activity than LBN. The catalysts were fully characterized by means of XRD, elemental analysis, N2-physisorption, H2-TPR, XPS, O2-TPD, NO-TPD and CO-TPD. These results demonstrated that the excellent catalytic performance of Ru/LBN catalyst was associated with the strong interaction between Ru and LBN, leading to enhancing reducibility and mobility of oxygen species and increasing the amount of the surface adsorbed oxygen. In addition, the amount of adsorbed CO and NO increased largely for Ru/LBN. And Ru3+ species on the surface of Ru/LBN was considered as an effective active site for NO + CO reaction. In-situ DRIFTS was used for studying the relationship between catalytic activity and NO, CO adsorption ability, species and sites. The results indicated that the new active species were formed on the surface of Ru/LBN compared with LBN including inorganic carboxylate, monodentate carbonate, Ru-NO, bridged nitrate and nitrite.

A serial of Rux-Co3O4 (x = 0.1, 0.2 and 0.3) catalysts were prepared by the coprecipitation method and applied to the decomposition of N2O. They were characterized by the XRD, TEM, Raman, H2-TPR, XPS, O2-TPD and in situ DRIFTS. The results indicate that the strong interaction between Co and Ru exists in the Rux-Co3O4 catalysts, which results in much larger BET surface area, better structural stability and more surface Co2+, Ru3+ and oxygen species compared with Co3O4. Additionally, the Rux-Co3O4 catalysts, especial Ru0.2-Co3O4, show much higher activity and stability than the Co3O4 catalyst due to the synergistic effect of Ru and Co3O4. Moreover, the Ru0.2-Co3O4 catalyst shows much stronger resistance against 2.1% H2O and 1.5% O2 in the feed than Co3O4.

A series of graphitized carbon (GC) supports with different degrees of graphitization was prepared and characterized. The study clearly showed that GC800 was the most proper support after loading the noble metal in the hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) to liquid fuel 2,5-dimethylfuran (DMF) under mild reaction conditions. Over the Pd/GC800 catalysts, relatively high selectivity to DMF was achieved, whereas the Au/GC800 catalysts displayed extremely low selectivity to DMF. Furthermore, PdAux/GC800 (x = 1–4) catalysts with different Au/Pd mass ratios were synthesized, which showed excellent catalytic activity without any activator or acidic media. More gratifyingly, the PdAu4/GC800 catalyst gave 94.4% DMF selectivity with 86.8% HMF conversion at 150 °C for 4 h and maintained good stability after five cycles, which was attributed to the intimate contact and intensive interaction between the Pd and Au nanoparticles. As a result, the dispersion of particles was improved, and the co...

Mn- or/and Ni-modified SAPO-34 molecular sieves (Mn–SAPO-34, Ni–SAPO-34, and MnNi–SAPO-34) were synthesized by a one-pot hydrothermal synthesis method using morpholine as a structure directing agent. XRD, XRF, SEM, TEM-EDX, UV-vis-DRS, NH3-TPD, XPS, NMR, and in situ DRIFTS analyses were performed to study the properties of the samples. The MnNi–SAPO-34 catalyst demonstrated much better NOx conversion (>95%) and N2 selectivity (>98%) for the selective catalytic reduction (SCR) of NOx by NH3 than those of the other catalysts from 320 °C to 470 °C. Moreover, NOx conversion could still be maintained at about 100% at 380 °C even after 80 h over MnNi–SAPO-34. Its excellent activity can be ascribed to the strong interaction between the Mn and Ni species in the framework of MnNi–SAPO-34, leading to the suitable redox ability of MnNi–SAPO-34 by the reaction Ni3+ + Mn3+ ↔ Ni2+ + Mn4+. The in situ DRIFTS results suggested that the NH3-SCR reaction was mainly performed by an Eley–Rideal (E–R) reaction pathway at 300 °C for the MnNi–SAPO-34 catalyst. Thus, MnNi–SAPO-34 is considered as a promising candidate for controlling NOx emissions at middle temperatures.

In this work, a series of NixMn1−xTi10 (x = 0.0–0.5) catalysts were synthesized using a one-pot sol–gel method for selective catalytic reduction (SCR) of NO with NH3. The effects of Ni doping on the catalytic activity and SO2 resistance were investigated by XRD, TEM-EDS, XPS, NH3-TPD, H2-TPR, SO2-TPD and in situ DRIFTS. It is found that the higher the amounts of surface Mn4+ and Oα species existing on the catalyst surface, the greater the oxidation ability that they present for NO and NH3, which results in better activity at low temperature and worse selectivity to N2 at high temperature due to the overoxidation of NH3. Among NixMn1−xTi10 (x = 0.0–0.5), the Ni0.4Mn0.6Ti10 catalyst exhibited excellent NH3-SCR activity, a wide temperature window (190–360 °C) and good H2O and SO2 durability even in the presence of 100 ppm SO2 and 15% H2O under a GHSV of 40 000 h−1, which is very competitive for the practical application in controlling the NOx emission from stationary sources. It is concluded that more surface Lewis acid sites and the appropriate contents of surface active Mn4+ and surface oxygen species on the surface of Ni0.4Mn0.6Ti10 play key roles in the special SCR performance due to the interactions among Mn, Ni and Ti oxides. The SO2-TPD and in situ DRIFTS results confirm the reason for the good SO2 resistance of the Ni0.4Mn0.6Ti10 catalyst. Moreover, in situ DRIFTS results reveal that the NH3-SCR reaction over Ni0.4Mn0.6Ti10 mainly follows the Eley–Rideal (E–R)-type mechanism.

In the present work, a serial of Cu

The low-temperature catalytic performance of Cu-ion-exchanged SSZ-52 catalysts (with different amounts of ion-exchanged Cu) for the selective catalytic reduction of NOx by NH3 (NH3-SCR) is investigated. The Cu-ion-exchanged SSZ-52 catalysts are prepared by a new method by using fumed silica as the silicon source. Among the synthesized Cux-SSZ-52 catalyst series, Cu2.4-SSZ-52 exhibits the highest NH3-SCR activity. In addition, the de-NOx performance of Cu2.4-SSZ-52 is superior to that of Cu2.4-SSZ-13. Moreover, the catalytic performance of Cu2.4-SSZ-52 reduces only slightly after hydrothermal aging at 750 °C. The microporous structure, redox ability, acidity properties as well as the location and nature of the Cu species and the reactant adsorption process of the support and Cux-SSZ-52 catalysts are investigated in detail. Overall, the findings show that the unique structure and cages of SSZ-52 are responsible for its excellent catalytic performance.

Cerium and titanium oxides are considered as promising alternative catalysts for selective catalytic reduction with NH3 (NH3-SCR) to remove NOx. However, the poor SO2 or H2O tolerance and stability limit their practical applications. Herein, CeTiOx with nanotube structure (CeTiOx-T) was prepared by hydrothermal method and used for NH3-SCR reaction. CeTiOx-T shows the excellent catalytic activity, SO2 and H2O tolerance and stability, in which more than 98 % NO conversion can be achieved in the range of 180−390 °C with 100 % N2 selectivity. The characterizations verify that CeTiOx-T exhibits amorphous structure due to the strong interaction between Ce and Ti to form short-range ordered Ce-O-Ti species. As results, CeTiOx-T displays the larger BET surface area, more surface Bronsted acid amounts and chemisorbed oxygen, leading to its higher NH3-SCR performance. In situ DRIFTS results suggest the SCR reaction mainly follow L-H and E-R mechanisms at low and high temperature for over CeTiOx-T, respectively.

A series of CoxCe1-xO2-δ (x = 0.05−0.6) oxides were synthesized through non-ionic surfactant hydrothermal method and applied for catalytic toluene oxidation. Various characterizations were performed to investigate the relation between structure and activity of the catalysts, including XRD, N2 adsorption-desorption, Raman spectra, TEM, H2-TPR, O2-TPD, XPS and in situ DRIFTS. CoxCe1-xO2-δ shows higher catalytic performance than pure Co3O4 and CeO2, meanwhile Co0.2Ce0.8O2-δ exhibits the best catalytic activity for toluene oxidation in the presence and absence of water, moreover, no obvious difference in activity among three successive testing runs. This good activity can be mainly attributed to the strong interaction between Co and Ce oxides to form Co0.2Ce0.8O2-δ solid solution, leading to abundant surface active oxygen species, more surface Co3+ and Ce3+ species. In situ DRIFTS is used to probe the catalytic reaction process, which reveals that toluene can be rapidly adsorbed and transferred to benzoate species, finally oxidized into CO2 and H2O.

Low acidity SAPO-34 was synthesized by adding seeding SAPO-34 as Si source without additional Si reagent, named as CSSAPO-34-x (x = 1, 2, 3) according to the seeding SAPO-34 content for 6 wt%, 8 wt% and 9 wt%, respectively. The characterizations prove that the CSSAPO-34-x samples display much lower Si content and acidity, good catalytic performance and light olefins selectivity in methanol to olefins (MTO) process compared with the seeding SAPO-34 and the similar Si content SAPO-34 synthesized in one pot procedure. Further studies demonstrate that Si distribution can be manipulated when the seeding SAPO-34 is recrystallized by the hydrothermal treatment, decreasing the acidity of the CSSAPO-34-x, leading to much better catalytic MTO performance.

The La1.6Ba0.4NiO4-x%BaO (x = 0, 5, 10, 15, 20, 25, 30) catalysts were prepared by heating the mixture of Ba(NO3)2 and La1.6Ba0.4NiO4 in situ, and their catalytic performances were evaluated for NO direct decomposition. The results showed that the activities of the La1.6Ba0.4NiO4-x%BaO catalysts had been improved with the increasing of BaO amount. Among these catalysts, the La1.6Ba0.4NiO4-20%BaO exhibited the best catalytic performance for NO direct decomposition, and the yield of N2 kept 57% during 500 h at 923 K in the absence of O2, even the concentration of O2 was 0.2% in the feed, the N2 yield still up to 57% at 923 K. So much higher activity for the perovskite(-like) oxides catalysts at such reaction temperature was first observed. In order to understand the role of BaO, a serial of experiments and characterizations were carried out on the La1.6Ba0.4NiO4-x%BaO catalysts. The results revealed that the number of chemical adsorption oxygen adsorbed on the oxygen vacancies increased and the mobility of the lattice oxygen could be improved due to the BaO addition. Moreover, BaO may play an important role in NOx transportation and storage, which is favorable for the regeneration of the active sites.

Ni(0.4)-MnO x catalyst was prepared by citrate combustion, which showed high catalytic performance for NH 3 -SCR reaction. After the resistance tests of SO 2 and H 2 O, Ni(0.4)-MnO x -SH showed better NH 3 -SCR activity than that of Ni(0.4)-MnO x , when the temperature was > 240 °C. The characterizations suggest that Ni(0.4)-MnO x -SH has more acid sites for ammonia adsorption and far weaker oxidation capacity for NH 3 , which resulted in the high catalytic activity at middle-temperature.

Pt–Co alloy supported on SBA-15 catalysts (Pt–Co/SBA-15) were prepared by impregnation and NaBH4 reduction method. Their catalytic performances were investigated for selective hydrogenation of cinnamaldehyde. It was found that the formation of Pt–Co markedly enhanced the conversion to cinnamaldehyde and selectivity to cinnamyl alcohol compared with Pt/SBA-15. Meanwhile, the Pt–Co/SBA-15-0.6 catalyst performed the best catalytic activity that 71 % CAL conversion and 91 % selectivity to COL were attained. Moreover, no obvious deactivation was observed after using 4 times for Pt–Co/SBA-15-0.6. This improvement was contributed to the formation of Pt–Co alloy, which increased the amount of the Pt0 species on the catalysts. Pt–Co alloy supported on SBA-15 catalyst shows excellent catalytic selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

Herein, a series of catalysts made of Pd–WN on various supports was synthesized by modifying supports with small-size WN NPs firstly and loading Pd subsequently. Their catalytic performances were evaluated for selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HALD). Interestingly, it was found the synergistic effect between Pd and WN can improve conversion and selectivity of CAL to HALD. Among these catalysts, Pd–WN/SBA-15 shows best performance with highest conversion (99 %) and selectivity to HALD (97 %), which is superior to commercial 5 % Pd/C catalyst. The hydrogenation kinetics of Pd–WN/SBA-15 has been adequately represented by a standard pseudo-first-order approximation, and it discloses that the existence of WN can effectively decrease the activation energy (23.2 kJ mol−1). The synergistic effect of Pd and WN results in enriching the electron density of Pd, increasing the ratio of surface Pd0 and decreasing the size of Pd on the Pd–WN/SBA-15 catalyst.