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Herein, we describe the development of highly active catalysts for the conversion of ethanol to 1,3-butadiene using high-throughput catalyst preparation and evaluation systems. Assuming a two-stage reactor for converting ethanol to acetaldehyde and ethanol/acetaldehyde to 1,3-butadiene, we conducted rapid screening for the optimal catalyst for each reaction. We found that using Ag/SiO2 and HfO2/SiO2 as catalysts in the first- and second-stage reactors, respectively, resulted in high 1,3-butadiene productivity (99% ethanol conversion and 63% 1,3-butadiene selectivity).

A two-dimensional reactor model based on reaction kinetics and heat and mass transfer for catalytic NH3 decomposition was constructed. A reactor design that minimizes the effect of endothermic reaction was investigated. It is difficult to design a single-tube reactor for NH3 treatment at a flow rate of 10 m3/h because heat transfer from the reactor wall cannot keep up with the fast consumption of heat by the reaction, even under low space velocity conditions. The target conversion was achieved by decreasing the NH3 supply rate. A reactor with a packed bed of suitable length was designed. Industrial-scale NH3 treatment can be achieved using a multi-tube reactor.

We accomplished zinc catalyzed hydrosilylation of carbon dioxide (CO2) to silyl formate (C+II), bis(silyl)acetal (C0), methoxysilane (C−II), and finally methane (C−IV). Among several zinc salts, we...

We prepared gold nanoparticles encapsulated in poly(amidoamine) (PAMAM) dendrimers as templating agents. The resulting gold nanoparticles were used as catalysts for the carboxylative cyclization of propargylic amines with carbon dioxide to afford the corresponding 1,3-oxazolidin-2-ones in yields of up to 99%.

The anti-Markovnikov addition of H2O to alkenes to directly bring in primary alcohols has been considered one of the “10 challenges in catalysis” in the 1990s, but the challenging issue has still remained unsolved over the past few decades, particularly in terms of developing an atom-efficient synthetic strategy. In this context, we introduce a novel access for the transformation of terminal alkenes with H2O into the corresponding primary alcohols over metal oxide-supported Pd catalysts, employing O2 as the sole oxidant. Direct and efficient synthesis of cinnamyl alcohol from allylbenzene and H2O was initially achieved as a fine chemical example over Pd(NO3)2/CeO2-ZrO2, and the target saturated alcohol (3-phenylpropan-1-ol) was obtained as the anti-Markovnikov selective product from a “one-pot” process using H2 as the reductant. The Pd(NO3)2/CeO2-ZrO2 was characterized by HAADF-STEM, XRD and X-ray absorption fine structure (XAFS) analyses, indicating that the molecular Pd(NO3)2 is probably deposited as it is on the support, which likely plays an important role to promote this reaction. In the second part, Pd(NO3)2/CeO2-ZrO2 and other supported Pd catalysts were applied for the transformation of 1,3-butadiene into 2-butene-1,4-diol in a batch reactor. Besides, butane-1,4-diol, which is an important industrial material, was efficiently produced by the simple hydrogenation of 2-butene-1,4-diol in a “one-pot” manner. Significantly, the development of the reaction catalyzed by supported Pd in a gas flow reactor bestows great potential to further industrial applications. Additionally, the adsorption structure of 1,3-butadiene on Pd(111) was confirmed as the s-trans form by infrared reflection absorption spectroscopy (IRAS) measurements. The change in the electronic states of surface Pd atoms upon oxygen adsorption was observed by X-ray photoelectron spectroscopy (XPS).

The effects of promoters on the performance of a VOx/SiO2 catalyst were investigated with the goal of increasing its catalytic activity for the oxidation of methane to formaldehyde. Fourteen types of metal oxides (MOx, M = Ga, In, Y, Al, Bi, Zr, La, Zn, W, Mg, Mo, Ti, Ce, and Ca) were tested as promoters. Among them, Ga2O3, In2O3, Y2O3, and Al2O3 substantially increased the methane conversion rate and the formaldehyde yield, whereas MgO, MoOx, TiO2, CeO2, and CaO were less effective as promoters. The catalytic activity also depended on the amount of the promoter and the method by which it was loaded onto the support. The highest activity was obtained over VOx/Ga2O3/SiO2 (V loading, 2–3 wt%; Ga loading, 0.1–0.5 wt%) prepared by a sequential impregnation method (Ga loaded first and then V): under the standard reaction conditions (reaction temperature, 590 °C; gas hourly space velocity, 60,000 L kg−1 h−1; CH4/O2 ratio, 2), the formaldehyde yield over this catalyst was 2.1 times that over bare VOx/SiO2. Reactions over the VOx/Ga2O3/SiO2 catalyst and the bare VOx/SiO2 catalyst showed different kinetics, indicating that Ga2O3 altered the properties of the active VOx sites. Catalyst characterization by means of X-ray diffraction and temperature-programmed reduction under H2 suggested that the high activity of VOx/Ga2O3/SiO2 was due to the promoter’s having increased the reducibility of the active VOx species without decreasing their dispersion.

The dehydrative allylation from allyl alcohol with amines to generate various allyl amines by MoO3/TiO2 solid catalyst is described. The catalyst can be reused at least three times without a decrease of activity.

A facile one-pot, phosgene-free method for the synthesis of N-phenylcarbamates is developed. Using this method, various aromatic carbamates could be prepared from aromatic amines, CO2 and metal alk...

The reverse water–gas shift reaction (RWGSR) using a supported ionic liquid-phase (SILP) catalyst consisting of Ru catalyst, ionic liquid (1-butyl-3-methylimidazolium chloride ([C4mim]Cl)), and porous silica gel support, was investigated. The catalytic activity of the SILP catalyst toward RWGSR strongly depends on the kind of Ru catalyst and amount of IL. Among the three kinds of Ru catalysts ([RuCl2(CO)3]2, Ru3(CO)12, and RuCl3), [RuCl2(CO)3]2 exhibits the best catalytic activity. Brunauer–Emmett–Teller (BET) surface area analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses of the SILP catalyst based on [RuCl2(CO)3]2 and [C4mim]Cl revealed that both the solvation of the active catalytic Ru species and the surface area of the ionic liquid phase strongly affect catalytic activity. Hence, these factors help to determine the optimum amount of [C4mim]Cl in the SILP catalyst. The resulting SILP catalyst, with an optimum constitution, exhibited greater catalytic activity than the homogeneous system in which the same amounts of [RuCl2(CO)3]2 and [C4mim]Cl were employed. Catalytically active Ru species during RWGSR in both systems were investigated by means of electrospray ionization-mass spectrometry (ESI-MS). Interestingly, the rate-determining step in the two systems was different, implying that the silica support lowers the activation energy of the protonation reaction in the catalytic cycle. Therefore, the facilitation of the RWGSR by a SILP catalyst system can be realized by good mass transport, derived from the large surface area, as well as the effect of the silica support on activation energy. Furthermore, 20 cycles of the RWGSR using the SILP catalyst were accomplished.

By employing tetrabutylammonium fluoride (TBAF) as a catalyst, the various carboxylative cyclizations of the propargylic amines having internal alkynes with CO2 proceeded to afford the corresponding 2-oxazolidinones. In this case, it was also found that the generated 2-oxazolidinones were tautomerized into the corresponding 2-oxazolones due to the basicity of TBAF. In addition, we performed the synthesis of quinazoline-2,4(1H,3H)-dione from 2-aminobenzonitrile and CO2 by using TBAF as a catalyst.

Etherification using allyl alcohol to produce allyl ether via dehydration is a fundamental technique for producing fine chemicals that can be applied to electronic devices. We demonstrate a sustainable method to synthesize allyl ethers from allyl alcohol with various alcohols up to a 91% yield, with water as the sole by-product. In this reaction, the active catalyst is gradually generated as the reaction proceeds through the simple mixing of TiO2 and MoO3. The dispersion of MoO3 on the spent catalyst has been observed by XRD, HAADF-STEM, and STEM-EDS mapping. This catalyst shows excellent catalytic activity by virtue of the highly dispersed nature of MoO3 supported on TiO2, which is reusable at least five times. According to a mechanistic study including the measurement of XPS of MoO3 on TiO2 and control experiments using SiO2 and Al2O3 supports, the suitable reducibility of MoO3 to coordinate the allyl moiety on TiO2 seems to be a key factor for high-yielding syntheses of various allyl ethers even under heterogeneous reaction conditions. The reaction mechanism is considered to be as follows: σ-allyl species are formed from dehydration of the allyl alcohol, followed by a nucleophilic attack by another alcohol against the σ-allyl carbon to give allyl ethers. The developed catalytic system should be suitable for easily handled syntheses of allyl ethers due to the employment of commercially available MoO3 and TiO2 with halide- and organic solvent-free reaction conditions.

Vapor phase catalytic transfer hydrogenation (CTH) of aqueous levulinic acid (LA) with formic acid as hydrogen source over different copper catalysts is reported. The Cu–SiO2 showed the highest LA conversion (56%) and selectivity to γ-valerolactone (GVL, 87%) at 250 °C. Analysis indicates that the presence of acid sites are responsible for the cleavage of C–O bonds forming angelicalactone intermediate followed by its hydrogenation to GVL over copper species. Even though the acid sites are necessary a quantitative correlation between acid sites and LA conversion was not observed. Characterization indicated that the higher conversion over Cu–SiO2 can be related to metal support interaction as evident from higher reduction temperature of copper species in H2-TPR compared to other catalysts.

The preparation of model Ziegler–Natta (ZN) surfaces under ultrahigh vacuum necessitates the activation of MgCl2 films deposited on a substrate, since these films unexceptionally expose the energetically most stable but catalytically inactive (001) face. Here, we present a method to activate MgCl2 films with the inactive (001) termination, which was based on the chemisorption of a Lewis base in an analogous way to industrial powder catalyst preparation. We found that a (001)-terminated MgCl2 film on Cu(110) was activated into a MgCl2·Lewis base adduct when exposed to a pyridine vapor at a nearly saturated vapor pressure. A dynamic response of the MgCl2 film to the chemisorption and desorption of a Lewis base was uncovered using low-energy electron diffraction and temperature-programmed desorption.

A series of ZrO2 catalysts supported on mesoporous SBA-15 silica were synthesized and examined as catalysts in the production of γ-valerolactone (GVL) from biomass-derived levulinic acid and its esters via a catalytic transfer hydrogenation (CTH) using several alcohols as hydrogen donors. Among the catalysts examined, ZrO2 supported on high-surface-area SBA-15 silica bearing highly-dispersed zirconium species exhibited the highest catalytic activity, of which reaction rate was 1.7 times higher than that of the conventional bulk ZrO2 catalyst. Zr K-edge XAFS analysis revealed that Zr4+-oxide species with a low-coordination state anchored on silica surface is the dominant active species. Such a Zr species efficiently converted levulinic acid and its esters to GVL (∼95% yields) under mild reaction conditions (150 °C, 1.0 MPa Ar), and was reusable over multiple catalytic cycles without significant loss of catalytic performances. Comparative experiments, combined with detailed characterizations using NH3/CO2-TPD and in-situ FTIR, proposed a plausible reaction mechanism where basic Zr OH site triggers the CTH reaction involving a six-member ring transition state.

In this work, the conversions of ethanol to propylene and ethylene to propylene were investigated over H-ZSM-5 zeolite catalysts with different SiO2/Al2O3 ratios (80 and 280). The effect of operating conditions (contact time and reaction pressure) has been studied. Special attention has been paid to the effect of reaction pressure on the propylene yield, space time yield and catalyst deactivation. Results show that the H-ZSM-5(280) catalyst was more stable for the ethanol or ethylene conversion reaction. High operating pressure favors the propylene production. However, the higher pressure leads to faster coking.

A flow manufacturing process was investigated for the synthesis of Pd@Pt core-shell nanoparticles (NPs) with high productivity and exact structural control. Pd@Pt core-shell NPs were successfully synthesized in a flow reactor using polyvinylpyrrolidone (PVP) as a capping agent. However, the oxygen reduction reaction (ORR) activity of the Pd@Pt/PVP/C catalyst was found to be significantly lower than that of commercial Pt/C as the remaining PVP inhibited ORR. In order to improve ORR activity, it is necessary to support the highly dispersed Pd@Pt NPs on activated carbon without the use of PVP. Cyclic voltammetry, transmission electron microscopy, and X-ray absorption fine structure analyses showed that Pd@Pt NPs could be uniformly dispersed on activated carbon by adding bis(2-methoxyethyl) ether (diglyme) as a capping agent. The particle size and core-shell structure of the Pd@Pt NPs did not differ significantly between the NPs synthesized with PVP or diglyme, indicating that advanced structural control was possible without PVP. Furthermore, the mass activity per Pt weight of the Pd@Pt/C catalyst using diglyme was found to be 1.8-fold higher than that of Pt/C. We thus succeeded in synthesizing Pd@Pt core-shell NPs with precisely controlled structure and high ORR activity by flow process.

Carbon supported Pd@Pt core-shell nanoparticles catalyst was prepared in a flow reactor toachieve enhanced catalytic activities with low Pt loading for the acceptorless dehydrogenative synthesis of pyrimidines. Spectroscopic (XAS analysis) and microscopic (HAADF-STEM) techniques reveled that the core-shell structure was formed by the applied preparation method. The Pd@Pt/PVP (polyvinylpyrrolidone)/C catalyst showed the activity for the three component one pot synthesis of pyrimidines through a series of consecutive reactions including oxidation of alcohols, C C, and C N coupling, followed by heterocyclization and dehydrogenation employing various primary alcohols, secondary alcohols, and amidines. The reaction mechanism on Pd@Pt/PVP/C catalyst was explored by comparison with the control experiments.

Dry reforming of methane at 400–600°C was studied over Rh catalysts with different supports (SiO2, γ-Al2O3, α-Al2O3, TiO2, ZrO2, CeO2, Y2O3, SiO2-Al2O3, SiO2-MgO, SiO2-TiO2), Rh particle sizes (1.5–15.6 nm), and acidic properties (acidic site density, 0.37–3.40 mmol g−1). Catalysts with a high density of strongly acidic sites (e.g., α-Al2O3, SiO2-MgO) showed low activity and gradually deactivated with time on stream; in contrast, catalysts with a low density of strongly acidic sites (e.g., TiO2, γ-Al2O3) showed high, stable activity. Rh/SiO2-TiO2 showed the best performance, with H2 and CO yields of 1.8% and 4.2% at 400°C and yields 37.3% and 53.1% at 600°C, respectively. Catalyst activity depended strongly on Rh particle size; specific activity increased with decreasing particle size, indicating that Rh-catalyzed dry reforming of methane is structure-sensitive. The support type influenced not only the dispersion and reducibility of the Rh particles but also the specific activity of the catalysts. CO temperature-programmed desorption and FT-IR suggested that electron-deficient Rhδ+ species were generated by electronic interactions between the Rh particles and the support, and the number of these species strongly influenced the overall catalytic activity.

The yttrium-modified zirconia catalysts were prepared by co-precipitation method. N 2 adsorption/desorption method, temperature programmed desorption and X-ray diffraction were used to characterize the Y/ZrO 2 catalyst. All the catalysts were tested in the conversion of ethanol to propylene. The propylene yields showed a volcano-shaped dependence on the Y amount. The maximum yield of propylene reached 44.0%. The results implied that Y/ZrO 2 catalyst with tetragonal structure or bigger specific BET surface area showed better performance. Reaction pathways were suggested to be ethanol to ethylene on the acidic sites, and ethanol → acetaldehyde → acetone → propylene on the basic sites.

Vapor phase catalytic transfer hydrogenation of aqueous levulinic acid (LA) with formic acid (FA) as a hydrogen source was carried out over copper loaded on to several SiO2 supports having different physicochemical properties. The SiO2 supports and Cu–SiO2 catalysts with different support properties were characterized by XRD, TPR, XPS, NH3-TPD and UV-vis techniques to evaluate the copper species and its interaction with the support. The SiO2 support alone showed lower LA conversion and low selectivity to GVL whereas Cu–SiO2 catalysts were found to show high conversion and selectivity to the desired product with formic acid as the hydrogen source. The difference in the activities and product selectivity among different copper supported silica appears to be a complex function of acidity and the nature of copper species in the Cu–SiO2 catalysts. No direct correlation was observed between a specific catalyst property such as acidity and pore size, and the performance of the Cu–SiO2 catalysts. From the characterization, it appears that the species responsible for higher activity and selectivity to GVL are monomeric partially oxidized copper species in a strong interaction with the support in combination with a higher number of acid sites, both of which are present in Cu–SiO2-Q6. Cu–SiO2-Q6 showed the highest conversion and selectivity of 66 and 81%, respectively, under optimized conditions.

Zeolites having a different pore size, pore geometry and acidity (small pore FER, medium pore ZSM-5, and large pore Y, BEA and MOR) were investigated for the conversion of levulinic acid (LA) to aromatics (BTX). Product selectivity was found to depend on pore size and radius of the zeolites. In addition to pore size, internal pore space, and steric hindrance play a determining role in aromatics production. ZSM-5 with moderate internal pore space and steric hindrance gave the highest BTX yield of 31% and least amount of coke. The high aromatic yield of ZSM-5 has been attributed to its strong acidity for cracking and suitable pore structure for aromatization.

We describe the reaction mechanism and active sites for CO oxidation over a Au/TiO 2 (110) model surface and Au single-crystal surfaces, along with the role of H 2 O, on a molecular scale. At low temperature ( 2 O played an essential role in promoting CO oxidation, and the active site for CO oxidation was the perimeter of the interface between the gold nanoparticles and the TiO 2 support (Au δ + -O δ - -Ti). We believe that the O-O bond was activated by the formation of OOH, which was produced directly from O 2 and H 2 O at the perimeter of the interface between the gold nanoparticles and the TiO 2 support, and consequently OOH reacted with CO to form CO 2 . This reaction mechanism explains the dependence of the CO 2 formation rate on O 2 pressure at 300 K. In contrast, at high temperature (>320 K), low-coordinated gold atoms built up on the surface as a result of surface reconstruction due to exposure to CO. The low-coordinated gold atoms adsorbed O 2 , which then dissociated and oxidized CO on the metallic gold surface.

The decomposition of NH 3 over Ni catalysts supported on various metal oxides (Y 2 O 3 , CeO 2 , MgO, La 2 O 3 , Al 2 O 3 , and ZrO 2 ) was investigated, and the Ni/Y 2 O 3 catalyst was found to show the highest activity. The rate of H 2 formation per exposed Ni atom (turnover frequency) for the supported Ni catalysts depended strongly on the type of metal oxide support, indicating that the active sites for the Ni catalysts were not identical in nature. Investigation of the associative desorption of atomic nitrogen formed by NH 3 decomposition over the Ni catalysts revealed that the N 2 desorption temperature depended on the type of support. This result indicates that the Ni N binding energy varied among the metal oxide supports, which would be attributable to the change of the Ni electronic state by the supports. The volcano-curve relationship was obtained between turnover frequency and N 2 desorption temperature, indicating that the NH 3 decomposition activity was dominated by the Ni N binding energy. We considered that the metal oxide supports changed the rate-determining step for NH 3 decomposition on Ni.

A layered double hydroxide (LDH) type adsorbent for phosphate removal from aqueous solution was prepared from blast furnace slag (BFS) which is vastly discharged by the iron manufacturing industry....

Side reactions of the ethanol-to-butadiene conversion catalyzed by MgO or ZnO were analyzed by density functional theory. We examined acetaldehyde disproportion to generate ethyl acetate, the hydrolysis of ethyl acetate to acetic acid, and the ketonization of acetic acid to generate acetone and CO2. The reactivities of these reactions on MgO and ZnO were compared. Our results revealed that among the three reactions, the difference in reactivity between the two oxides was greatest for the ketonization reaction—there was a higher activation barrier on MgO than on ZnO. This would cause the higher ratio of by-products on ZnO than on MgO.

By employing only silica as a catalyst, the carboxylative cyclization of a propargylic amine with CO2 proceeded to afford the corresponding 2-oxazolidinone. MCM-41, which was a mesoporous silica, was found to be the most effective silica for this purpose. Moreover, after the reaction, the MCM-41 catalyst was recovered by filtration and could be reused over ten times without deactivation.

In this study, H-ZSM-5 catalysts with different particle sizes were prepared by adding different amount of water to the starting gel before crystallization. These H-ZSM-5 catalysts were characterized by scanning electron microscopy, N2 adsorption/desorption measurements, X-ray fluorescence, X-ray diffraction, and temperature programmed desorption of ammonia. It was found that the olefin (ethylene, propylene and butene) yield decreased with the increase in the particle size of the catalysts. The paraffin (ethane, propane and butane) yield trended to increase with the increase of particle size. The C5 + products yield increased considerably with the increase of particle size. The results implied that the formation of the C5 + products and hydrogen was inhibited over the smaller particle size catalyst, furthermore the formation of paraffin decreased. So the propylene yield could be increased over smaller H-ZSM-5 catalyst.

Kattel et al . (Reports, 24 March 2017, p. 1296) report that a zinc on copper (Zn/Cu) surface undergoes oxidation to zinc oxide/copper (ZnO/Cu) during carbon dioxide (CO 2 ) hydrogenation to methanol and conclude that the Cu-ZnO interface is the active site for methanol synthesis. Similar experiments conducted two decades ago by Fujitani and Nakamura et al . demonstrated that Zn is attached to formate rather than being fully oxidized.

Gold–palladium bimetallic nanoparticle catalysts prepared by a deposition–precipitation method were effective for aerobic oxidation of glycerol to carboxylic acids. The role of palladium was to suppress C–C bond cleavage that is responsible for the formation of C2 by-product molecules. The nanoparticles were observed by microscope techniques, which further enabled characterizing the respective locations of Au and Pd within the particles.