Haoxi Jiang

Catalytic activity of transition metal doped Cu(111) surfaces for ethanol synthesis from acetic acid hydrogenation: a DFT study

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.

1,3-Butadiene Production from Bioethanol and Acetaldehyde over Zirconium Oxide Supported on Series Silica Catalysts

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 3.6–11.6xa0nm 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.Graphical Abstract

The deactivation of a ZnO doped ZrO2–SiO2 catalyst in the conversion of ethanol/acetaldehyde to 1,3-butadiene

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.

Conversion of Ethanol and Acetaldehyde to 1, 3-Butadiene Catalyzed by Zr–Si Materials

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.

Selective Catalytic Reduction of NO x with NH 3 on Cu-BTC-derived Catalysts: Influence of Modulation and Thermal Treatment

In this work, copper-based metal organic frameworks Cu3(BTC)2 (BTCu2009=u20091,3,5-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.

Metal-organic framework loaded manganese oxides as efficient catalysts for low-temperature selective catalytic reduction of NO with NH 3

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-% MnOx 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 MnOx/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 MnOx and the Zr oxide secondary building units of the UiO-66 which has a positive effect on the catalytic activity. The 8.5 wt-% MnOx catalyst maintained excellent activity during a 24-h stability test and exhibited good resistance to SO2 poisoning.

CeO2–ZrO2–Al2O3 Ternary Oxides Synthesized via Supercritical Anti-Solvent and as a Support for Pd Catalyst for CO Oxidation

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.