Catalytic hydrochlorination of Si is an effective route to manufacture trichlorosilane (TCS), the main feedstock of high-purity Si for solar cells. However, the understanding of its catalytic process is still limited. Herein, we prepared CuO catalysts modified with Fe2O3 promoter (Fe2O3-CuO) by one-step hydrothermal method and investigated their catalytic performance for producing TCS. Compared with the non-catalytic case, pure CuO catalyst, and the Fe2O3-CuO-M catalyst obtained by mechanically mixing CuO with Fe2O3, the Fe2O3-CuO catalyst exhibits the highest TCS selectivity and Si conversion. The introduction of Fe2O3 facilitates lattice oxygen migration of CuO due to the electron interactions between Fe2O3 and CuO. During the reaction, CuO transforms into CuCl2 and CuCl2·2H2O, then to CuCl. The latter is the key intermediate for forming the active CuxSi phase. This work discloses the transformation of the CuO catalyst during the Si hydrochlorination reaction, and provides new insights into the catalytic mechanism.

The behavior of palladium-phosphorus catalysts deposited on a Na-ZSM-5 zeolite support, in the direct synthesis of hydrogen peroxide under mild conditions has been studied. It was found that elemental phosphorus exerts a promoting effect on the activity and selectivity of Pd catalysts for synthesizing H2O2. A direct relationship between the P:Pd ratio (in the range P:Pd = 0: 1.0) and the activity of the catalysts is shown. The influence of phosphorus on the properties of palladium catalysts in side reactions: decomposition and hydrogenation of H2O2 is considered. The chemical and phase composition of Pd-P particles was studied by ICP, HRTEM, electron diffraction, and XRD methods. The modifying effect of phosphorus on the properties of Pd catalysts in the direct synthesis of H2O2 is associated with the formation of solid solutions between palladium and phosphorus, an increase in the dispersion, and the surface roughness of Pd-P particles.

Cationic manganese (MnP - [Mn(T4MPyP)]5+) and anionic iron (FeP - [Fe(TDFSPP)]3–) metalloporphyrins in conjunction with zinc oxide of different morphologies, were synthesized. After characterization by different instrumental techniques, the metalloporphyrins were immobilized on the obtained zinc oxide and the catalysts were evaluated regarding the oxidation of cyclohexane, using iodosylbenzene (PhIO) as model oxidant. In the absence of light, the activities of FeP/ZnO were higher than those obtained by neat ZnO and MnP/ZnO. Furthermore, under the reaction conditions of 1:100:1000 catalyst/oxidant/substrate, with acetonitrile as solvent, for 1 h at 25 °C without any radiation source, the reactions were selective for ketone. The same occurred for the neat FeP under homogeneous conditions. In contrast, when the reaction proportions were changed to 1:20:1000 catalyst/oxidant/substrate and when the catalyst amount was increased 10 times, the selectivity was for alcohol. Under irradiation with a dichroic halogen lamp (50 W), all the systems containing FeP showed higher selectivity for alcohol, while when MnP was used, increments like those with FeP were not observed, probably due to the structural differences between FeP and MnP. This FeP to MnP replacement led to spectral differences that might have been responsible for the inability of MnP to interact efficiently with the radiation emitted by the dichroic halogen lamp as well as promoting the higher amount of ketone produced in comparison with the FeP/ZnO system.

Herein, the Co-MMT (Co3O4-montmorillonite) catalysts were prepared by coordination-deposition (Co(0.015)-MMT-2(CD)) and deposition-precipitation method (Co(0.015)-MMT-2 (DP)) for the N2O direct decomposition, respectively. The structure, texture, and surface properties of the catalysts are characterized by XRD, TEM, FT-IR, Raman, XPS, and so on. The results show that compared with Co(0.015)-MMT-2(DP), Co(0.015)-MMT-2(CD) achieves barrier dispersion of active phase (Co3O4) by using the layer structure of montmorillonite and has a smaller Co3O4 crystal size, richer oxygen vacancy and higher content of Co2+Oh. In addition, the results of DFT calculation and kinetic calculation indicate that Co2+Oh possesses higher reaction activity than Co2+Td and Co3+Oh, and the TOF value of Co(0.015)-MMT-2(CD) at 400 ℃ is 3 times higher than that of Co(0.015)-MMT-2(DP). Therefore, the Co(0.015)-MMT-2(CD) catalyst shows excellent catalytic activity and tolerance to impurity gases (H2O, NO, and O2), and it can maintain 100% conversion at least 50 h for the direct catalytic decomposition of N2O.

A series of zirconium phosphates (ZrP-x) with various P/Zr ratios were prepared. Among the catalysts, ZrP-2.5 with a high specific surface area of 410.9 m2·g−1 and abundant mesopores exhibited outstanding catalytic performance in the synthesis of p-xylene (PX) from 2,5-dimethylfuran (DMF) and ethylene. A high PX yield of 89.2% and a productivity of 72.3 mmolPX·gcat−1·h−1 were achieved at 250 °C using a small amount of catalyst. The excellent catalytic performance of ZrP-2.5 was attributed to the synergy between the large quantities of acidic sites with appropriate acid strength distribution, balanced Brønsted and Lewis acidity, and abundant mesopores. In addition, the catalyst had excellent recyclability and stability. In-situ FT-IR spectra of adsorbed DMF and ethylene revealed the crucial roles of P-OH and the coordinately unsaturated Zr(IV) in the adsorption and reaction process, which is beneficial to understanding the reaction mechanism and designing highly efficient catalysts.

Dehydration of biomass-derived 1,4-butanediol (1,4-BDO) is an attractive approach to synthesizing 1,3-butadiene (BD), which is a useful monomer for various polymers and currently produced via naphtha cracking. Cerium oxide (CeO2) with weak acid-base bifunctionality promoted the dehydration of 1,4-BDO to BD in 66% yield with 80% selectivity under the optimized conditions. The selectivity given by the CeO2 catalyst was influenced by the calcination temperatures, since the acid-base bifunctionality and reducibility of CeO2, which were examined temperature-programmed analyses, were altered. In stark contrast, the catalysts with strong acid sites exemplified by SiO2-Al2O3 and H-type mordenite (H-MOR) were inappropriate for this reaction since they produced tetrahydrofuran as a major product. The control experiments using a set of substrates suggested that 3-butene-1-ol was the main intermediate in the 1,4-BDO-to-BD dehydration, and its isomer of 2-butene-1-ol was also involved in the reaction but rather triggered the undesired side reactions to form butyraldehyde and ketones.

A family of heterojunction photocatalysts C60/TpPa have been constructed from fullerenes (C60) and TpPa-1 via in-situ solvothermal method firstly. The photocatalytic activity toward CO2 of C60/TpPa has been evaluated through the gas-solid reaction system under pure CO2 and low concentration CO2 (10 %) atmosphere, respectively. The results show that the maximum CO formation rates for C60/TpPa are as high as 48.16 μmol·g−1·h−1 and 90.25 μmol·g−1·h−1 under pure CO2 and 10 % CO2 environment, respectively. The attractive experimental phenomenon is assigned to the existence of CO groups in TpPa-1. Due to the presence of Z-scheme heterojunction, the separation of photoexcited electrons and holes is effectively enhanced, and the photocatalytic performances are significantly improved. This work suggests that the construction of COF-based photocatalysts with heterojunction for efficient photoreduction of CO2 is a promising strategy.

The catalytic activity of unsupported NiMoS catalysts prepared in situ by thermal decomposition of the [(CH3)3S]2Ni(MoS4)2 precursor was studied in the course of diphenyl ether hydrodeoxygenation. The resulting catalysts were characterized using the transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was demonstrated that the diphenyl ether conversion naturally decreases with a decrease in the precursor loading. The effect of changes in the amount of the added sulfiding agent on the morphological and structural features of the formed catalysts was studied. It was found that reducing the amount of elemental sulfur from 2.5 to 0.5 wt% results in a more active sulfide NiMo catalyst, which is explained by an increase in the dispersion of the active phase particles from 0.24 to 0.34. A route of diphenyl ether hydrodeoxygenation on unsupported NiMoS catalysts was studied and suggested by varying the reaction time and hydrogen pressure in the system.

Rigorous emission regulations and the advancements in combustion engines have forced researchers to develop new strategies for removing CO at low temperatures. The Cu/CeO2-ZrO2 (Cu/CZ) catalyst has received an extensive attention due to its low cost and high CO oxidation activity at low temperatures. Nonetheless, the poor thermal stability of Cu/CZ remains as a major challenge for practical applications. In this study, we systematically investigated the effect of La doping on the hydrothermal stability of Cu/CZ. The La-doped catalyst, Cu/CZL, retained a high CO oxidation ability even after thermal aging at 800 °C for 20 h. La doping not only helped preserve the surface-active oxygen and oxygen storage capacity of Cu/CZ during thermal aging, but also enhanced its ability to efficiently convert intermediate surface carbonate species into CO2. These promoting effects of La resulted in the excellent CO oxidation activity over the aged-Cu/CZL under the simulated exhaust condition, significantly outperforming the conventional counterpart, PtPd/γ-Al2O3.

Gas phase dehydration of 1,3-butanediol was studied at 523 K on solid catalysts with different acidic and physicochemical properties: Al2O3, SiO2/Al2O3, NaZSM5, HZSM5 and TPA (tungstophosphoric acid)/SiO2. The solids were characterized by N2 physisorption, DRX and FTIR spectroscopy of pyridine. The main products were butadiene and 3-buten-1-ol via dehydration route, in addition to propene plus formaldehyde and 4-methyl-1,3-dioxane by reverse or direct Prins condensation, respectively. The effect of reaction temperature (473-573 K) on 1,3-butanediol conversion and products distribution was evaluated. The relationship between the nature of catalytic sites and the main reaction pathway was analyzed. Catalysts with Brønsted acid sites promoted the dehydration reaching the highest yield of butadiene (75%) on TPA/SiO2 while Lewis acid sites favored the inverse Prins reaction route to propene and formaldehyde. Further studies using the possible intermediates of 1,3-butanediol dehydration were performed and probable mechanisms of formation of the different products were proposed.

Zeolitic octahedral metal oxide based on niobate (ZOMO-NbOx) with high acidity is synthesized as an effective catalyst for fluoroquinolone antibiotics degradation under visible light. Higher acidity promoted the adsorption of ciprofloxacin (CIP), a represented fluoroquinolone antibiotic, on ZOMO-NbOx. The adsorption of CIP on ZOMO-NbOx enables the material to expand the light-absorbing region from UV to visible range through the ligand to metal charge transfer. ZOMO-NbOx shows high catalytic activity with the total over frequency (TOF) value (22.27 μmolCIP min-1 gcat-1), which is 53 times higher than of the commercial Nb2O5 (0.42 μmolCIP min-1 gcat-1). The stable heterogeneous ZOMO-NbOx is reused 5 times without loss of activity. ZOMO-NbOx shows good resistance to inorganic ions and humic acids (HAs), and CIP is able to be degraded by the catalyst from various natural freshwater bodies. The intermediate products are determined, and the degradation pathways are proposed.

Tubular ionizers are dielectric barrier discharge devices widely employed for indoor air purification. Nonetheless, their practical application is limited by low efficiency and high concentrations of harmful by-products, such as ozone. To address these challenges, we have developed a new approach to integrate tubular ionizers with catalysts by uniformly spraying MnO2 catalysts onto the tubular medium. This synergistic coupling of plasma and catalysis significantly enhances the catalytic performance, leading to near twofold increase in the conversion of HCHO, while reducing ozone concentrations to two-thirds of those in the plasma-only system. We have also developed a fluorescence probe to detect the presence of free radicals such as HO• and O2−•. Our results demonstrate that the catalyst loading generates more hydroxyl and superoxide radicals, leading to superior catalytic performance.

From sustainable development and application standpoint, visible-light-driven oxidation of sulfides is emerging as sizzling focuses. In this work, a series of novel polyoxometalate-based photocatalysts, PW12-M@COFs 1 − 3 (M = Ag+ 1, Cu2+ 2, Ni2+ 3) were successfully synthesized via the electrostatic interactions between POM anion and cationic porous M@COFs, which were characterized by infrared (IR) spectroscopy, EDS analysis, solid diffuse reflective spectroscopy etc. These compounds exhibit strong visible light adsorption and can be used as excellent photocatalysts for the oxidation of sulfides to sulfoxides and the degradation of chemical warfare agent simulant, 2-chloroethyl ethyl sulfide (CEES). Especially, compound 1 with Ag+ has the best catalytic activity, achieving 98% of methyl phenyl sulfide conversion with 99% of selectivity in 3.5 h illuminated by a 10 W 425 nm light-emitting diode (LED). When extended to other sulfur-containing compounds, it also demonstrates satisfactory yield to sulfoxide and degrade CEES within 2 h. The mechanism reveals that both singlet oxygen and superoxide radicals act as the reactive oxygen species for the visible-light-driven oxidation of various sulfides, corresponding to the photoinduced electron-transfer and energy-transfer pathways. Moreover, these catalysts exhibited excellent catalytic and structural stability.

Titania-supported ruthenium (Ru/TiO2) is an established catalyst for the hydrogenation of carbon dioxide to methane (Sabatier reaction). Chlorine contamination, owed to the RuCl3 precursor, is demonstrated to have a detrimental impact on methanation activity. After calcination and reduction the catalyst contains residual chlorine, shown by XPS. An aqueous ammonia wash removes Cl without leaching Ru. The washed catalysts exhibit improvements in CH4 site-time yields. Low Ru loading catalysts encounter the greatest activity enhancements after washing (∼4.5–fold). DFT calculations indicate that chlorine and CO2 directly compete for adsorption on Ru step sites, with Cl impeding the adsorption of CO2 at under-coordinated sites and at higher Cl coverages. H2-chemisorption/TPR show that Cl removal lowers the onset of low temperature H2 dissociation on Ru. DRIFTS provide evidence that the removal of Cl facilitates low temperature dissociative binding of CO2, indicated by the formation of surface bound linear CO species.

The morphology effect of TiO2 on the dispersion of molybdena species and the performance of the resulting MoOx/TiO2 catalysts in selective oxidation of isobutene to methacrolein were examined. Two-dimensional MoOx monolayers in Mo–O–Mo bonds were well dispersed on TiO2 nanosheets that were preferentially enclosed by the {001} facets. However, aggregated MoOx clusters enriched in terminal MoO bonds were formed over TiO2 nanospindles dominated by the {101} facets. The superior performance of the MoOx monolayers, regarding activity, selectivity and stability, was ascribed to the synergetic effect between MoOx monolayers and TiO2 (001) facets.

Recently, the research of co-crystallized zeolites and their application in heterogeneous catalysis are very active. Herein, the synthesis of MOR/ZSM-5 co-crystallized zeolites is achieved via a facile OSDA-free and seed-assistant hydrothermal method. The prepared samples are characterized by XRD, FT-IR, SEM, N2 adsorption-desorption and 27Al/29Si MAS NMR to systematically evaluate the effects of crystallization time on the structural properties. The results reveal that the phase compositions of the crystalline products switch from ZSM-5 to co-crystallized MOR/ZSM-5 and finally to MOR with the extending of crystallization time from 12 to 72 h, where common composite building units play a vital role. Furthermore, the synthesized M/Z-48 catalyst exhibits a remarkable catalytic activity and stability in the alkylation of toluene with ethanol due to the reasonable acidity and textural properties provided by the composite structure of MOR and ZSM-5 zeolites.

In this study, the direct synthesis conditions of dimethyl carbonate (DMC) from methanol and CO2 were controlled under the dual supercritical conditions, whose temperature was higher than the maximal critical temperature of CO2 and methanol (>239 ℃), and the partial pressure for each reactant was larger than its partial critical pressure (PCO2 > 7.4 MPa and Pmethanol > 8.1 MPa). A series of CeO2 catalysts with different morphologies including traditional nanorod, amorphous and flower structures were synthesized by hydrothermal method. The prepared catalysts were characterized by the BET, XRD, SEM, NH3/CO2-TPD, XPS, and H2-TPR, and the results indicated that flower CeO2 performed the largest acid-base sites and oxygen vacancies as expected, proving its superior physicochemical properties and catalytic activity. Moreover, the catalytic activity synthesis of DMC from CO2 and methanol was investigated, confirming that the flower CeO2 owned the highest catalytic performance, and the maximum yield of DMC was 3.11 mmol/gcat. under the reaction conditions (16 MPa, 250 °C, reaction time of 1 h without stirring). Importantly, the synthesis kinetic mechanism of DMC in dual supercritical systems was experimentally studied using the synthetic CeO2 catalysts, and the flower CeO2 catalyst possessed the lowest apparent activation energy of 45.9 kJ/mol, meanwhile, the initial reaction rate equation obtained from the experiment can be represented as: Rate = k [*] [CH3OH] [CO2]1/2, which was consistent with the reaction mechanism of Langmuir–Hinshelwood type.

Heck reaction is one of the effective routes to form C-C bond, however the process still suffers problems from the separation and low-temperature activity of catalysts. Herein, Pd nanoparticles supported on SiC was prepared by a sample impregnation-reduction process. The Pd/SiC photocatalyst exhibited a high iodobenzene conversion of 99.6 % with 100 % selectivity to methyl cinnamate under visible light irradiation at 40 ℃. The excellent performance is due to the good light absorption ability of Pd/SiC and effective charge separation through Mott-Schottky junction between Pd and SiC. The electron-rich Pd nanoparticles are favorable to activate C-I bond of iodobenzene, thus enhancing the photocatalytic activity for Heck reaction of iodobenzene and methyl acrylate.

In the new field of plasma-catalytic synthesis, iron-based catalysts have been intensively studied but no study was reported on the use of potassium promoter although it is widely used in thermo-catalytic synthesis. In this frame, we study the effect of K-promoter on iron-based plasma-catalytic conversion of CO2 and CH4 into higher value products, through a series of experiments with and without potassium. As expected, K-promoter increases the selectivity of unsaturated hydrocarbons but also that of long-chain oxygenates (C3 + acids and alcohols), by changing the H-adsorption property of the catalyst. Based on this selectivity tuning way, this paper proposes a first process optimization attempt for maximizing at the same time the production of liquid products and the share of unsaturated hydrocarbons. Coproduction of high quality syngas (H2/CO∼2.0), C2 + hydrocarbons and C1 + oxygenates with 5.10% CO2 and 12.65% CH4 conversions, 21.76% liquid selectivity and unsaturated over saturated hydrocarbons ratio close to 1.

Relative initial reaction rates for both double bond isomerization and direct esterification with heptanoic acid were determined for the series of linear 1-alkenes from 1-octene to 1-octadecene. In competitive reactions between two 1-alkenes on Amberlyst®15 catalyst at 90 °C, rates for both double bond isomerization and esterification decreased with increasing carbon chain length. Data suggested each 1-alkene had two different adsorption coefficients on the catalyst, one for an isomerization site and one for a site for the addition reaction. Results were consistent with previous data suggesting that Amberlyst®15 catalyst has two different types of active sites.