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Heteroatom zeolites with a high content of framework metal sites as Lewis-acid catalysts via improved dissolution–reconstruction strategy.

In this work, Ta was firstly reported as an efficient promoter of MgO–SiO2 for the conversion of ethanol and acetaldehyde to 1,3-butadiene. The doping of Ta into MgO–SiO2 forms Ta–O–Si bonds and generates more strong Lewis acid sites, which not only promote the aldol condensation reaction but also significantly facilitate the Meerwein–Ponndorf–Verley reduction, the total conversion around 80% which drops to 65% after 24 h. In addition, the catalyst showed desirable stability in 24 h long-term stability evaluation, the selectivity remained stable at 80%.

Highly dispersed palladium nanoparticles (NPs) supported on UiO-66 as catalyst for CO2 methanation were prepared by supercritical fluid deposition (SFD). As a result, the most suitable Pd precursor salt and co-solvent are Na2PdCl4 and ethanol/DMF, respectively. The best SFD process condition to deposit the Pd precursor on UiO-66 is 40 °C, 10 MPa and 2 h. Under the above condition, 4% Pd/UiO-66 exhibits the highest activity with 53% of CO2 conversion and 95% of CH4 selectivity while the turnover frequency (TOF) value is 3669.4 h−1. The catalysts were characterized by XRD, BET, TEM, XPS, TGA, CO-DRIFTS and ICP-OES to investigate the structure–activity relationship. The 4% Pd/UiO-66 with the average size of 2.2 nm of Pd prepared in assistance of supercritical fluid behaved the similar activity as the 6%Pd/UiO-66 with average size of 9.7 nm of Pd prepared by sol–gel method. It is showed prospect of technique for reducing noble metal loading resulting from high dispersion effect.

Naphtha catalytic reforming is an important process due to the production of BTX (benzene, toluene, and xylene) using platinum-based catalysts, in which tin can be used as a second metal to improve the catalytic performance. In this work, the influence of different Sn salts and precursor salts with different Sn/Pt ratios on the structure–activity relationship of Pt–Sn/Al2O3 prepared by supercritical fluid deposition is studied systematically. Results showed that when Na2PtCl6 and SnCl2 are used as precursor salts, the metal particle size of Pt–Sn/Al2O3 is the smallest at 0.7 nm; bimetals exist in the form of PtSn alloy and its catalytic reforming activity is also the best. An increase in the Sn/Pt ratio will further reduce the particle size of Pt and increase its dispersion. When the Sn/Pt ratio is 1.5, it shows the best catalytic activity. The metal particle size of the catalyst has a great influence on the dehydrogenation process of methylcyclopentane (MCP), showing an obvious size effect. The dehydrogenation performance of the Pt–Sn/Al2O3 prepared by the SFD method is significantly higher than that of the catalyst prepared by the impregnation method. By increasing temperature, pressure and liquid space velocity, the conversion of MCP, the selectivity of benzene and the production capacity of benzene are further improved.

The catalytic hydrogenation of CO2 to methanol has been regarded as the one of the most economical and effective ways to reduce CO2 emissions. It can also provide a feasible idea for solving the energy crisis. In this paper, a series of Pd/In2O3/SBA-15 catalysts were prepared by the citric acid method. The DFT simulation and catalyst characterization including the N2 adsorption, XRD, H2-TPR, TEM, XPS and CO2-TPD were applied. The results showed that the as-prepared Pd/In2O3/SBA-15 catalysts exhibited superior catalytic activity with 83.9% methanol selectivity and 12.6% CO2 conversion, corresponding to a STY of 1.1 × 10-2 mol·h-1·gcat-1 under reaction conditions of 260 °C, 5 Mpa and 15,000 cm3 h-1·gcat-1. It is suggested that the synergetic effect of H2 dissociation on Pd species and CO2 activation on In2O3 promoted the high efficiency conversion of CO2 to methanol.

This paper has systematically investigated the structures and properties of the ZrO2, Nano-SiO2 and their composition. The catalysts were prepared by impregnation, characterized by N2 adsorption–desorption, TEM, XRD, Raman, temperature-programmed desorption of NH3 and CO2, FTIR spectroscopy of adsorbed pyridine and CO2, and UV–vis spectra. Compared with dry-mixed samples, these catalysts have larger average pore diameter, enabling ZrO2 to be dispersed more uniformly on the surface of Nano-SiO2. With the Zr–O–Si bonds, ZrO2 could interact intensely with Nano-SiO2. The catalyst prepared shows the best performance, with the selectivity of 93.18% and conversion of 58.52%. The preparation methods have a significant influence on the interaction between ZrO2 and Nano-SiO2, which then affects the acid–basic properties. This paper finds that weak acid–basic sites with moderate-intensity are more suitable for ethanol conversion to BD, with the amount of acid and basic sites as close as possible.

MnO2–CoOX catalysts with different Mn/Co ratios were prepared using polyvinyl pyrrolidone (PVP) as an assistant to control the morphology and exposed crystal faces of composite oxides. The physicochemical properties of the catalysts were systematically characterized and the catalytic activity of NH3-SCR and resistance to SO2/H2O were investigated. It was found that the NO conversion over Mn–Co-0.2-PVP was apparently higher compared with that over Mn–Co-X-PVP (X = 0.9, 0.8, 0.6, and 0.4). This can be interpreted in terms of exposed crystal surface (110) and enhanced adsorption of NH3/NO, and better redox performance resulting from higher Co3+/Co2+ ratio. Furthermore, different PVP and HAc additives have different H2O and SO2 resistance. Mn–Co-0.2-PVP showed good resistance to H2O and SO2 poisoning owing to having more low-temperature (∼200 °C) NO adsorption sites, which are beneficial to promote the de-NOX reaction and less affected by SO2.

Upgrading bio-ethanol into high value chemicals is an important issue in biomass conversion, and conversion of ethanol into butadiene is one of the most feasible methods. Here Zr-incorporating mesoporous SBA-15 (Zr–SBA-15) materials with different Si/Zr ratios were successfully synthesized by a one-pot method and were employed as catalysts for the conversion of the ethanol (EtOH)–acetaldehyde (AcH) mixture to butadiene. The textural structure and acidity of Zr–SBA-15 were investigated by using XRD, N2 adsorption, TEM, FT-IR, UV-vis, XPS, NH3-TPD and Py-IR, and the results of these characterizations indicated the mesoporosity of Zr–SBA-15 and confirmed the incorporation of Zr into the framework. Zr–O–Si bonds were formed by the incorporation and exhibited Lewis acidity predominantly. The influence of the Si/Zr ratio and reaction conditions (temperature, EtOH/AcH ratio and WHSV) showed that a suitable Si/Zr ratio was needed to balance the butadiene selectivity, by-product selectivity and total conversion. Amongst the prepared catalysts, Zr–SBA-15-20 achieved the best butadiene selectivity of 74.0% at a relatively low temperature (275 °C). The good catalytic performance could be attributed to the homogeneous dispersion of Zr species and Zr–O–Si bond generated by Zr incorporation. Furthermore, EtOH-TPD and AcH-TPD experiments proved the essential role of acetaldehyde addition and the well-accepted reaction pathway.

Direct ethanol fuel cell technology suffers from a lack of effective anode catalysts for complete ethanol oxidation reaction (EOR). Pd and Pd-based catalysts showed some promise, but only a trace a...

There is a required need for improving low-temperature selective catalytic reduction with ammonia (NH3-SCR) activities of catalysts. In this paper, Cu-SAPO-34 and Mn/Cu-SAPO-34 catalysts were prepared by a one-pot hydrothermal synthesis method. ICP-OES, N2 adsorption/desorption, XRD, FT-IR, SEM, H2-TPR, XPS, NH3/NO-TPD were performed to study the properties of the catalysts. Mn promoted Cu-SAPO-34 shows considerably improvement in low-temperature NH3-SCR activity with almost 100% NOx conversion between 220–300 °C. It is suggested that the excellent catalytic activity of Mn/Cu-SAPO-34 is ascribed to MnO2 which can promote “fast-SCR”. H2O/SO2 resistance tests were also investigated and the results show that the catalysts both exhibit strong resistance to H2O but the introduction of Mn doesn’t improve the SO2 resistance of Cu-SAPO-34.

The supported copper based catalysts could be potential candidate for the selective catalytic hydrogenation of acetic acid to produce ethanol instead of noble metals. In this work, a series of highly efficient bimetallic Cu-In/SBA-15 catalysts were designed and prepared via the deposition-precipitation method. Detailed characterizations were carried out to investigate the textural properties, dispersion and chemical state of the metals, the interactions between copper and indium species, the adsorption and activation of acetic acid on the catalysts surface. The results clearly demonstrated the coexistence of Cu-In alloy and metallic Cu under the reductive reaction atmosphere. The strong synergistic effect inside Cu-In alloy not only accelerated the dissociation of acetic acid to acetate, but also hindered the combination of acetyl and ethoxy species to form ethyl acetate, thus promoting the catalytic hydrogenation performance significantly. It was also found that the concentration of adsorbed H atoms on catalysts was one of the indispensable factors affecting the ethanol selectivity, which was positively correlated to the exposed Cu surface area and H2 partial pressure. The optimal catalytic hydrogenation activity was obtained for 9Cu1In/SBA-15 under the reaction conditions of 2.5 MPa and 623 K, the conversion of acetic acid and selectivity of ethanol reached 99.1% and 90.9%, respectively. These results might provide an inspiration in the rational design of novel copper based catalysts for carboxylic acid hydrogenation.

Carbon dioxide methanation is of great importance for both environment and energy because of the reduction of carbon dioxide emissions and the utilization of carbon source. In this work, UiO-66 was employed as the support for palladium nanoparticles via a sol-gel method to enhance the activity of CO2 methanation. The physical-chemical properties of as-prepared catalysts were characterized using N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscope (TEM), temperature programmed desorption (TPD), temperature programmed reduction (TPR), thermo-gravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that there was a synergistic effect between UiO-66 and supported Pd. CO2 could be activated in UiO-66 via its Zr6O4(OH)4 nods, while H2 molecules were dissociated at Pd for further hydrogenation of activated CO2. As a result, the catalyst with a Pd loading of 6 wt.% exhibited a high activity with 56.0% of CO2 conversion and 97.3% of CH4 selectivity, corresponding to a STY of 856 g·h−1·kgcat−1 at 4 MPa and 340 °C.

A series of α-MnO2 catalysts doped with Fe, Ce, Cr, Zr, or Co as metal promoters were synthesized via a hydrothermal method. The effects of these metal promoters on the physicochemical properties and deNOX activity of the α-MnO2 catalysts were systematically investigated, among which α-MnO2 catalyst doped with Co behaved with the best selective catalytic reduction (NH3-SCR) activity at low temperatures. The α-MnO2 catalyst with Mn/(Mn + Co) = 0.8 (molar ratio) displayed an outstanding NH3-SCR activity with 100% NO conversion between 140 and 280 °C, excellent N2 selectivity and stability which may be due to plenty of acid sites, a strong adsorption capacity for NH3/NO at 100–300 °C, and abundant Mn4+, Co3+, and surface adsorbed oxygen species. Further, the catalyst exhibited excellent H2O/SO2 resistance and the NO conversion activity remained 100% after adding 5% H2O, 200 ppm of SO2, or 5% H2O + 100 ppm of SO2 at 200 °C.

The low-temperature selective catalytic reduction (SCR) of NOx by ammonia is an efficient purification technique to eliminate NOx from stationary combustion sources. In this paper, the different exposed crystal facets of α-MnO2 catalyst were controllably synthesized by using of capping agents of PVP, P123, HAc and CTAB. It was found that all α-MnO2 catalyst prepared using various capping agents are with the same nanorods morphology but different exposed crystal facets. The structure-activity relationship of the catalyst was investigated and the exposed crystal facets showed strong effects of on its activity of SCR for deNOx. The α-MnO2 catalyst with exposed (2 0 0) facets has the highest surface acidity, strongest NH3 and NO adsorption and therefore the best low-temperature SCR activity, with 98% NO conversion at 160 °C.

Series of ZrO2 supported on the different kinds of SiO2 carriers were applied in the reaction of 1, 3-butadiene formation from ethanol and acetaldehyde. ZrO2/Nano-SiO2 performed the best performance with the 1, 3-butadiene selectivity 91.43% and the total conversation 52.39%. Prepared catalysts were characterized by N2 adsorption–desorption, TEM, XRD, temperature-programmed desorption of NH3 and CO2, FTIR spectroscopy of adsorbed pyridine and CO2, Raman XPS. The results show that the weak Lewis acid and basic sites are appropriate for BD formation. Furthermore, more and balance acid-basic sites are rather important for the reaction of ethanol and acetaldehyde conversion to BD.

Single-phase Co/Mn-MOF-74 solid materials were synthesized successfully via the hydrothermal method. The effect of Co/Mn atom ratio on the structure of Co/Mn-MOF-74 solids and their catalytic activity for low-temperature NH3-SCR of NOx were investigated. Very high NO conversion values (>96.0%) at 180–240 °C were obtained using the Mn0.66Co0.34-MOF-74 chemical composition (optimal content of Co). Furthermore, Mn0.66Co0.34-MOF-74 showed outstanding resistance to SO2 poisoning and the incorporation of Co was shown to cause the weakening of the SO2 adsorption strength on the catalyst surface, thus to enhance catalyst's SO2 resistance to poisoning. These features were probed by in situ DRIFTS and catalytic performance studies. The present work suggests that Mn0.66Co0.34-MOF-74 could be likely considered as a prospective industrial NH3-SCR NOx control catalyst.

In this paper a series of zirconium oxide supported on silica composite oxides were studied as catalysts for the production of 1,3-butadiene from bioethanol and acetaldehyde. The highest selectivity observed was 91.43%. Different silica materials with varied pore diameters in the range of 3.6–11.6 nm and the service life of the catalyst have been initially investigated. The catalysts were characterized by a nitrogen adsorption analysis, X-ray diffraction, scanning electron micrography and 29Si solid-state NMR spectroscopy. The catalytic results show that the pore sizes are important factors determining the activity when catalyst contains a subtle balance of the acid and base.

In this work, copper-based metal organic frameworks Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylatle), were applied in the conversion of toxic oxynitride into nitrogen at low temperature. Scanning electron microscope (SEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XRD) and other characterization methods were employed to fully understand the properties of the catalysts. We introduced acetic acid into the synthesis process as the modulator of the crystal structure and morphology. The catalytic assessment indicated that compared with the prototype, modified Cu-MOFs materials obtain enhanced catalytic activity for the SCR reaction. Besides, several thermolysis experiments were conducted to explain structure–function relationship.

Developing a new type of low-cost and high-efficiency non-noble metal catalyst is beneficial for industrially massive synthesis of alcohols from carboxylic acids which can be obtained from renewable biomass. In this work, the effect of active oxygen vacancies on ethanol synthesis from acetic acid hydrogenation over defective In2O3(110) surfaces has been studied using periodic density functional theory (DFT) calculations. The relative stabilities of six surface oxygen vacancies from Ov1 to Ov6 on the In2O3(110) surface were compared. D1 and D4 surfaces with respective Ov1 and Ov4 oxygen vacancies were chosen to map out the reaction paths from acetic acid to ethanol. A reaction cycle mechanism between the perfect and defective states of the In2O3 surface was found to catalyze the formation of ethanol from acetic acid hydrogenation. By H2 reduction the oxygen vacancies on the In2O3 surface play key roles in promoting CH3COO* hydrogenation and C–O bond breaking in acetic acid hydrogenation. The acetic acid, in turn, benefits the creation of oxygen vacancies, while the C–O bond breaking of acetic acid refills the oxygen vacancy and, thereby, sustains the catalytic cycle. The In2O3 based catalysts were shown to be advantageous over traditional noble metal catalysts in this paper by theoretical analysis.

A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO2–SiO2 catalyst prepared by a sol–gel method was performed. The samples were characterized by N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), NH3 temperature programmed desorption (NH3-TPD), X-ray powder diffraction characterization (XRD), thermogravimetric analyses (TGA), Fourier transform infrared resonance (FT-IR), 13C magic-angle spinning nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). The pore structure characteristics and surface acidity of Zn0.5–Zr–Si catalysts were largely decreased with time-on-stream and no crystal structure was formed in the used catalyst, indicating that the deactivation was caused by carbon deposition. Two main types of carbon deposition were formed, namely low-temperature carbon deposition with the oxidation temperature of around 400 °C and high-temperature carbon deposition with the oxidation temperature of 526 °C. The carbon species were mainly composed of graphitized carbon, amorphous carbon, carbon in C–O bonds and carbonyls. The deactivated catalyst could be regenerated by a simple oxidation process in air. Adding a certain amount of water into the feed had a positive effect on reducing the carbon deposition.

The conversion of bioethanol to 1,3-butadiene (ETB) is expected to be one of the most promising routes to alternate the petroleum route. However, the preparation of hierarchical β zeolite to serve as the catalyst support is still challenging. In this work, hierarchical β zeolite was prepared through protective desilication by quaternary ammonium hydroxide (TAAOH), and Zr-β zeolite was prepared using the hierarchical β zeolite by dealumination-metallization strategy for ETB reaction. The mechanism of protective desilication was clarified by some control experiments. The protection of TAA+ coexists with OH- attacking and they act in different treating stage, and there lies the best treatment concentration regarding to the mesoporous formation in β zeolite. By adjusting the length of TAAOH alkyl chain, the mesoporosity of β zeolite was tuned successfully. The catalytic activity of Zr-β zeolite was enhanced by the generation of mesoporosity and better capability of coke was achieved which mitigated the deactivation.

The selective catalytic reduction (SCR) of NO x with NH 3 has been proven to be an efficient technology for NO x conversion to N 2 . However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning which seriously limits their practical application. This review summarized sulfur poisoning mechanisms of various SCR deNO x catalysts and strategies to reduce deactivation caused by SO 2 such as doping metals, controlling the structures and morphologies of the catalysts, and selecting appropriate supports. The methods and procedures of catalysts preparation and the reaction conditions also have effect on SO 2 -resistance of the catalysts. Several novel catalyst systems that exhibited good SO 2 resistance are also introduced. This paper could provide guidance for the development of highly efficient sulfur-tolerant deNO x catalysts.

A mild in-situ deposition method was used to fabricate Mn-based catalysts on a UiO-66 carrier for the selective catalytic reduction of NO by NH3 (NH3-SCR). The catalyst with 8.5 wt-% MnO x loading had the highest catalytic activity for NH3-SCR with a wide temperature window (100–290 °C) for 90% NO conversion. Characterization of the prepared MnO x /UiO-66 catalysts showed that the catalysts had the crystal structure and porosity of the UiO-66 carrier and that the manganese particles were well-distributed on the surface of the catalyst. X-ray photoelectron spectroscopy analysis showed that there are strong interactions between the MnO x and the Zr oxide secondary building units of the UiO-66 which has a positive effect on the catalytic activity. The 8.5 wt-% MnO x catalyst maintained excellent activity during a 24-h stability test and exhibited good resistance to SO2 poisoning.

Density functional theory (DFT) calculations were employed to theoretically explain the reaction mechanism of acetic acid hydrogenation to ethanol on Cu catalyst. The activation barriers of key elementary steps and the adsorption configurations of key intermediates involved in acetic acid hydrogenation on Cu(111) surface were investigated. The results indicated that the direct dissociation of acetic acid to acetyl (CH3COOH → CH3CO + OH) is the rate-determined step. The activation barrier of acetic acid scission to acetyl and the adsorption energy of acetic acid are two descriptors which could determine the conversion of acetic acid. The descriptors might have effects on the ethanol selectivity including: the adsorption energy of acetaldehyde and the activation barriers for O H bond formation of C2-oxygenates (CH3CO + H → CH3COH, CH3CHO + H → CH3CHOH and CH3CH2O + H → CH3CH2OH). These proposed descriptors could be used as references to design new Cu-based catalysts that have excellent catalytic performance.

The conversion of ethanol to butadiene catalyzed by modified β zeolites has attracted wide attention. The construction of intracrystalline mesoporosity in β zeolite is a challenging way to improve the catalytic activity. In this work, a surfactant-template strategy was used to construct intracrystalline mesoporosity successfully in the alkali treatment of β zeolite using long-chain quaternary ammonium salt with different alkyl chain length (C10~C16) as the template. The intracrystalline pore size can be adjusted by varying the surfactant alkyl chain length (C10~C16) (1.9–3.4 nm). To get more information about this process, CTAB was chosen as the template in further investigations. The mesoporosity can be generated within 1 h. The BET surface area can reach up to 600 m2/g while the pore volume can reach up to 0.568 cm3/g, which are 1.23 and 1.5 times that of the parent zeolite, respectively. The template action of CTA+ is essential for forming mesoporosity, and CTA+ interacts with the zeolite during the alkali treatment process, protects the zeolite framework from being etched, and does not form a separated mesoporous phase. To demonstrate the effect of intracrystalline mesoporosity on the catalytic performance, Zr-β zeolite was prepared and used as the catalyst for ethanol-acetaldehyde conversion. The hierarchical Zr-β zeolite was prepared using a dealumination-metallization strategy, and both the zeolite crystallinity and the mesoporosity were preserved in this process. The total conversion increased by 10%, while the BD selectivity was well maintained. The catalytic performance showed that the introduction of mesoporosity effectively mitigated decreasing conversion while preserving BD selectivity.

CeO2–ZrO2–Al2O3 ternary oxides as a support for CO oxidation was synthesized successfully via supercritical anti-solvent (SAS) precipitation using CO2 as the anti-solvent and methanol as the solvent. It was found that the CeO2–ZrO2–Al2O3 fabricated by SAS precipitation (CZA1) had superior resistance to sintering compared to the traditional co-precipitation method (CZA2). Meanwhile, the oxygen storage/release rate of CAZ1 was almost 1.5 times higher than that of CZA2 and the total oxygen storage capacity (OSC) of CAZ1 was almost twice as high as CZA2. The interactions between the Pd and the CeO2–ZrO2–Al2O3 support were stronger for the support synthesized by SAS precipitation. The conversion of CO oxidation of Pd/CZA1 was even better than that of Pd/CZA2, especially at high GHSV.

Transition metal (Co, Ni, Ru, Rh, Pd and Pt) doped Cu(111) models are selected to examine the effects of transition metals on Cu surface for ethanol synthesis from acetic acid hydrogenation using density functional theory (DFT) calculations. On these surfaces, the adsorption of the main intermediates and reaction barriers of key elementary steps are investigated. The calculation results indicate that oxophilic metals are projected to be more active in acetic acid adsorption and acetaldehyde adsorption compared to less-oxophilic metals. Those metals with larger C adsorption energies generally have better C–OH bond cracking activity. Additionally, a good linear Bronsted–Evans–Polanyi (BEP) correlation is established for predicting the preferences of C–OH bond scission of acetic acid on other metals. Finally, O–H bond formation in C2-oxygenates (CH3CO, CH3CHO, CH3CH2O) hydrogenation is examined on all these surfaces. The reactions are more likely to occur on less-oxophilic metal-doped Cu surfaces. Therefore, it appears to involve an intricate balance between C–OH cracking and O–H bond formation reactions. That means those metal-doped Cu-based catalysts that are capable of preferentially activating C–OH bond without considerably inhibiting O–H bond formation of C2-oxygenates are predicted to achieve optimum catalytic activity for ethanol synthesis from acetic acid hydrogenation. The results can provide theoretical guidance for related experiments as well as the designing of Cu-based catalysts for ethanol synthesis.

Developing low-cost and high-efficiency non-noble metal catalysts is beneficial for industrially massive synthesis of ethanol from acetic acid, which can be obtained from renewable biomass. Understanding the detailed mechanism of the reaction from a molecular level provides insights that can be used to tailor catalysts to improve their performance. In this study, alternative mechanisms for ethanol synthesis from acetic acid hydrogenation over Cu2In(100) have been investigated using periodic density functional theory (DFT) calculations. The pathway of CH3COOH → CH3COO → CH3CHOO → CH3CHO → CH3CH2O → CH3CH2OH was found to be most favorable. The high activation barriers for CH3COO hydrogenation to CH3CHOO (1.33 eV) and CH3CH2O hydrogenation to CH3CH2OH (1.04 eV) indicate that these two steps are the rate-limiting steps. In addition, the results also show that there are probably two more active intermediate species of CH3CO and CH3CH(OH)O besides CH3COO. Furthermore, the synergy and the role of copper and indium in the Cu–In bimetallic catalyst were discussed. The adsorption strength of copper will be improved by indium. Indium, however, has high chemical inertness in Cu2In. They evenly divided the surface into small reaction areas which could significantly inhibit ethyl acetate formation through the hindrance effect.

Direct ethanol fuel cell technology is impeded by inefficient, yet expensive anode catalysts. As such, research on effective and cheap anode catalysts towards complete ethanol oxidation reaction (EOR) is greatly needed. Herein, we report the investigations of the competitive C–C and C–H bond scissions in the EOR involving CH3CO, CH2CO, and CHCO species on Cu(100) using density functional theory and transition state theory calculations. The easiest C–C bond cleavage was found in CH2CO while the most difficult C–H bond cleavage was also found in CH2CO, both with an activation energy of 1.02 eV. The feasible C–C bond scission may take place in CH2CO with a rate constant ratio of the C–C to the C–H bond scission at 100 °C of 0.32. Furthermore, in an alkaline environment, the C–H bond scission activation barrier is considerably lowered but the C–C bond cleavage activation barrier is slightly increased for both CH3CO and CH2CO species. The reaction of CH3CO species on Cu(100) under alkaline conditions produces mainly acetic acid with a barrier of 0.49 eV and a rate constant of 4.93 × 105 s−1 at 100 °C.

Hollow CuO-CeO 2 -ZrO 2 nano-particles were prepared with supercritical anti-solvent apparatus by using methanol as solvent and supercritical carbon dioxide as anti-solvent. Two key factors (i.e., pressure and temperature) were investigated to explore the effects of catalyst structure and physic-chemical properties (i.e., morphology, reducing property, oxygen storage capacity and specific surface area). The resulting materials were characterized with X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), hydrogen temperature programmed reduction (H 2 -TPR) and oxygen storage capacity (OSC) measurement, respectively. The experimental results showed that lower temperatures promoted production of hollow structure nano-particulates. The particle morphology also changed significantly, i.e. the solid construction was first transferred to hollow structure then back to solid construction. The optimal conditions for obtaining hollow nano-particles were determined at 45 °C, 18.0–24.0 MPa.

In this work, Mn-MOF-74 with hollow spherical structure and Co-MOF-74 with petal-like shape have been prepared successfully via the hydrothermal method. The catalysts were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry–mass spectrum analysis (TG-MS), N2 adsorption/desorption, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It is found that MOF-74(Mn, Co) exhibits the capability for selective catalytic reduction (SCR) of NOx at low temperatures. Both experimental (temperature-programmed desorption, TPD) and computational methods have shown that Co-MOF-74 and Mn-MOF-74 owned high adsorption and activation abilities for NO and NH3. The catalytic activities of Mn-MOF-74 and Co-MOF-74 for low-temperature denitrification (deNOx) in the presence of NH3 were 99% at 220 °C and 70% at 210 °C, respectively. It is found that the coordinatively unsaturated metal sites (CUSs) in M-MOF-74 (M = Mn and Co) played important role...

Co-MOF-74 materials were synthesized at different temperatures using solvothermal method. The effect of the synthetic temperature on the structure and low temperature NH3-SCR catalytic performance of Co-MOF-74 was systematically investigated. Co-MOF-74 synthesized at 100 °C has flower-like morphology, while hexagonal prism structures could be obtained at other temperatures. Co-MOF-74 with flower-like morphology has a larger specific surface area and pore volume compared with the hexagonal prism ones. The highest catalytic activity was obtained at 200 °C under the optimal synthesis temperature, which was attributed to the combination of special morphology, the highest specific surface area and Co content.

Highly dispersed platinum nanoparticles (NPs) supported on alumina were prepared by supercritical fluid deposition (SFD) with the aid of co-solvent ethanol using inorganometallic Na2PtCl6·6H2O as Pt precursor. The mean Pt particle size (1.5 nm) was obtained at the optimized deposition conditions of 40 °C and 110 bar and 3 h of deposition time. The catalysts were characterized by high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), CO diffuse reflectance infrared Fourier transform spectroscopy (CO-DRIFTS), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES) and hydrogen-oxygen titrations to investigate the structure-activity relationship. Compared with the catalyst prepared via an impregnation method, the Pt was highly dispersed to smaller particles for Pt/Al2O3 catalysts prepared by SFD and showed much higher catalytic activity of catalytic reforming of cyclohexane dehydrogenation.

A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO

Highly dispersed Ru nanoparticles (NPs) supported on carbonaceous materials were fabricated by supercritical fluid deposition technology and characterized by various methods including high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The mean particle size was controlled in the range from 0.42 to 3.66 nm by changing the carbonaceous support or the pretreatment method of the supports. Ru NPs supported on carbon nanotubes (CNTs) presented smaller particle size, higher dispersion and catalytic activity than those on activated carbon (AC). The interactions between Ru precursors and different carbonaceous supports were characterized by hydrogen temperature programmed reduction (TPR). The ultrasonication-assisted nitric acid oxidation pretreatment method for CNTs is favorable for the dispersion of Ru NPs. The appropriate ultrasound time and the dosage of nitric acid are the prerequisites of its good performance. The optimized pretreatment conditions are ultrasound time 20 min and nitric acid dosage 1/14 (the mass ratio of CNTs to HNO3).

超临界流体技术作为一种绿色技术在多孔材料合成领域受到了研究者的广泛关注.与传统方法相比较, 利用超临界CO 2 制备多孔材料的方法具有方法简单、环保、产品性能好等优点, 且CO 2 无毒、价廉、原料易得, 具有很好的工业应用前景.本文概述了近年来超临界CO 2 在分子筛、碳纳米管、金属/复合氧化物纳米粒子、金属有机骨架材料、聚合物等多孔材料的合成方面的应用和研究进展.

Sulfonated mesoporous carbon catalysts were synthesized using a carbonization–sulfonation method and employed to the pre-esterification of free fatty acids contained in high acid value oil. Various synthesis parameters, such as composition of carbon precursor, carbonization and sulfonation temperature, were systematically investigated. The catalysts were characterized by N2 adsorption, small angle XRD, HRTEM, FT-IR and strong acid density analysis. The results indicated that they have a high surface area, uniform pore size, large mesopore volume, high acid density and good catalytic activity. Among them, MC600-S160 exhibited a highest activity and good stability for the esterification of FFA with methanol, the FFA conversion reached 94.6% after reaction for 3 h.

Spherical mesoporous MnO x nanoparticles were prepared by the thermolysis of a Mn-MOF-74 template. The morphologies of the MnO x nanoparticles were inherited from the Mn-MOF-74 template and the crystal structures of the MnO x particles could be regulated by changing the thermolysis conditions. These porous MnO x nanoparticles were tested as low-temperature selective catalytic reduction (SCR) catalysts and they exhibited high activities. The sample prepared at 700 °C under a N 2 atmosphere had the largest specific surface area (89.1 m 2 /g) and the highest deNO x activity (98% NO conversion) with a N 2 selectivity of almost 100%.

Developing a new type of low-cost and high-efficiency non-noble metal catalyst is beneficial for industrially massive synthesis of alcohols from carboxylic acids which can be obtained from renewable biomass. In this work, the effect of active oxygen vacancies on ethanol synthesis from acetic acid hydrogenation over defective In

Developing low-cost and high-efficiency non-noble metal catalysts is beneficial for industrially massive synthesis of ethanol from acetic acid, which can be obtained from renewable biomass. Understanding the detailed mechanism of the reaction from a molecular level provides insights that can be used to tailor catalysts to improve their performance. In this study, alternative mechanisms for ethanol synthesis from acetic acid hydrogenation over Cu

A series of carbon-based solid acid catalysts were prepared from bagasse using a carbonization–sulfonation method and employed to catalyze esterification of oil with methanol to produce biodiesel. The physical and chemical properties of the biomass carbon catalysts were characterized by FTIR. The pretreatment of bagasse, carbonization temperature, sulfonation temperature and time, as well as the catalytic performance were systematically investigated. The results indicated that the catalysts prepared from bagasse with dilute acid hydrothermal treatment showed the best performance. For the catalysts, the acid value of waste cooking oils was decreased to 1 mg KOH/g, and FFA conversion reached 94.4 % after reaction for 4 h under optimized reaction conditions. The catalysts also showed better stability than traditional homogeneous catalysts.

Ordered mesoporous carbon (OMC) supported ferric sulfate (FS) catalysts were prepared by impregnation, and their catalytic activity for the esterification of the free fatty acids (FFAs) in waste cooking oil (WCO) with methanol was evaluated. The FS/OMC catalysts were characterized by N 2 adsorption–desorption, powder X-ray diffraction and transmission electron microscopy. The results indicated that catalysts retained the ordered mesoporous structure, and the FS was well dispersed on the surface of the OMC. The FT-IR spectrum of pyridine adsorbed on the FS/OMC catalysts showed the presence of strong Lewis acid sites on the surface of the catalysts. The FS/OMC catalysts exhibited excellent catalytic performances for FFA esterification. In addition, the process variables that influence the esterification of FFAs, such as the FS loading, the amount of catalyst, the molar ratio of methanol to FFAs, the reaction temperature and the reaction time, were investigated and optimized. The FS/OMC catalysts are reusable and maintained their original catalytic activities after six uses.

Ru catalysts supported on activated carbon (AC) were prepared by supercritical fluid deposition (SFD) with ethanol added and their catalytic performance in butanone hydrogenation was investigated. The effects of ethanol amount on Ru particle size were systematically studied. As the amount of ethanol increased, Ru mean particle sizes always decreased firstly, then increased. And the minimum mean particle size of Ru was obtained at 10 ml ethanol. The catalysts with smaller Ru mean particle size presented higher catalytic activity. These results demonstrated that the role of ethanol may not be only co-solvent but also anti-solvent and extractant during the preparation of Ru/AC.

A novel phosphorylated ordered mesoporous carbon (POMC) solid acid catalyst has been prepared by modifying mesoporous carbon with phosphoric acid, and was employed to catalyze the esterification oleic acid with methanol. The effects of the carbonization temperature on the type of phosphorus species formed, the phosphorus content and the amount of acid in the POMC were investigated. A mechanism for the phosphorylation of the ordered mesoporous carbon is proposed. The POMCs have good catalytic activity for the esterification of oleic acid and showed good reusability.