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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.

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.

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 this paper, the activity and stability of Ru supported on La1.6Sr0.4NiO4 perovskite-like catalysts prepared by two different methods, incipient wetness procedures with the addition of ethylene glycol (Ru/LSN-EG) and without ethylene glycol (Ru/LSN), were investigated for the decomposition of N2O. The catalysts were fully characterized by means of XRD, elemental analysis, N2-physisorption, TEM, H2-TPR, N2O-TPD and XPS. The Ru/LSN-EG catalyst retained high activity for 10 h without deactivation, which is attributed to the stable Ru3+ species, the much higher mobility of lattice oxygen and the regeneration ability of oxygen vacancies. However, the Ru/LSN catalyst presented deactivation; the initial N2O conversion of about 95% was only maintained for the first hour and decreased with time to 55% after 6 h. The reasons for this deactivation were investigated by a series of experiments and characterizations. The results indicate that the deactivation of the Ru/LSN catalyst can be ascribed to the difficult desorption of the oxygen species derived from N2O decomposition on the active sites; moreover, all the metallic Ru and Ru3+ species are oxidized to high oxidation state Ru4+ species. All the results demonstrated that the Ru3+ species was more favorable for N2O decomposition. Furthermore, the effects of O2 and H2O on the decomposition of N2O were also evaluated over the Ru/LSN-EG catalyst. High stability and no irreversible deactivation of the Ru/LSN-EG catalyst, even in the presence of O2 and H2O, were found.

The introduction of a suitable co-catalyst is a promising way to improve the catalytic efficiency of Pt catalysts. Herein, SBA-15 modified with well-dispersed Mo2N nanoparticles (NPs) is synthesized by anchoring phosphomolybdic acid (HPM) on aminated SBA-15 (SBA-15-NH2) primarily, followed by nitridation treatment under NH3. After loading of Pt, the Pt–Mo2N/SBA-15 catalyst with close-contact Pt and Mo2N NPs can be formed. The intensive interaction of Pt and Mo2N benefited from the close contact is verified by XRD and XPS tests. As a result, the ternary Pt–Mo2N/SBA-15 catalysts have shown superior performance to Pt/SBA-15 catalysts for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. The TOF over the 1 wt% Pt–Mo2N/SBA-15 catalyst is close to that over the 3 wt% Pt/SBA-15 catalyst, but its selectivity to cinnamyl alcohol (COL) is 2.5 times that of 3 wt% Pt/SBA-15. The promoted activity of Pt–Mo2N/SBA-15 is mainly attributed to the synergistic effect of Pt and Mo2N NPs, which can cause the full development of the catalytic ability of Pt, thus reducing the Pt usage, through increasing the dispersion of Pt NPs and the fraction of Pt0 species in the catalyst.

A series of CeaTiOx catalysts with different Ce/Ti molar ratios was prepared by a sol–gel method and used for selective catalytic reaction (SCR) of NO with NH3. The NO conversion values confirmed that the Ce0.3TiOx catalyst showed a much higher activity at low temperature, and the catalyst exhibited 100% NO conversion in the broad temperature range of 200–350 °C and nearly 100% N2 selectivity. The catalysts were characterized by the BET surface area, XRD, XPS, NH3-TPD and H2-TPR. These results demonstrated that the excellent catalytic performance of the complete amorphous Ce0.3TiOx catalyst was associated with the strong interactions between Ce and Ti, the higher BET surface area, abundant acid sites, and greater presence of Ce3+ and chemisorbed oxygen. In situ DRIFTS was used for studies of the reaction mechanism and SO2 resistance. The results indicate that the L–H reaction pathway can be hindered in the presence of SO2 at low temperature ( 200 °C) led to a satisfactory SO2 resistance.

A series of 25% KF–La2O2CO3 catalysts (25-KF–LOC-x, x = 673, 723 and 773) were prepared at different calcination temperatures, which were tested as basic catalysts for the transesterification of tributyrin with methanol to produce methyl butyrate and characterized by means of XRD, SEM, CO2-TPD, FTIR, XPS and XRF. It was found that the calcination temperature greatly influences the catalytic activity, and its order is 25-KF–LOC-673 < 25-KF–LOC-723 < 25-KF–LOC-773. Especially, the 25-KF–LOC-773 catalyst exhibits a very high activity, and the conversion of tributyrin is nearly 100%, the yield of methyl butyrate reaches 94% at 308 K. The activation energy of the 25-KF–LOC-773 catalyst is as low as 55.03 kJ mol−1. The excellent catalytic activity of the 25-KF–LOC-773 catalyst can be attributed to the largest amount of surface hydroxyl among these 25-KF–LOC-x catalysts. The results indicate that the Bronsted base is the main active site at low reaction temperature. The recycling use and stability have been investigated over the 25-KF–LOC-773 catalyst. The results indicate that the 25-KF–LOC-773 catalyst has a high stability after being stored for 90 days. The deactivation of the used 25-KF–LOC-773 catalyst at 308 K is due to the loss of hydroxyl on the surface. However, the conversion of tributyrin can reach 91%, and the yield of methyl butyrate also can achieve 64% when the transesterification reaction is performed at 338 K over the second used 25-KF–LOC-773 catalyst. It indicates that the second used 25-KF–LOC-773 catalyst still possesses good catalytic activity at the higher reaction temperature due to the unchanged strong Lewis basic sites provided with surface oxygen anions.