Novel fabrication of copper oxides on AC and its enhanced catalytic performance on oxidative carbonylation of methanol

Copper oxides（CuOx） nanoparticles dispersed on activated carbon（AC） were prepared by using vaporphase methanol as the reducing agent. The CuOx/AC as prepared exhibited an enhanced catalytic activity in oxidative carbonylation of methanol to dimethyl carbonate（DMC）. The catalytic performance was significantly influenced by reduction conditions including temperature and time. With the similar selectivity of DMC, the space time yield（STY） under optimal reduction conditions reached up to 408 mg g^-1h^-1, which is superior to conventional methods such as thermolysis and solvothermal reduction. Based on the characterization results of XRD, TEM and XPS, the good copper dispersion and high Cu^＋ content obtained by vapor-phase methanol reduction were mainly responsible for the high catalytic activity.

Effects of potassium promoter on the performance of PdCl_2–CuCl_2/AC catalysts for the synthesis of dimethyl carbonate from CO and methyl nitrite

The effect of potassium （K） promoter on the catalytic performance of activated carbon （AC） supported Wacker-type catalysts （PdCl2-CuCl2/AC） for the synthesis of dimethyl carbonate （DMC） from CO and methyl nitrite （MN） was investigated by means of N2 adsorption, H2-temperature-programmed reduction （H2-TPR）, and X-ray photoelectron spectroscopy （XPS）. The experimental results showed that the space time yield of DMC on Wacker-type catalysts with different K promoters ranked in the following order： KCI 〉 KOH 〉 CH3COOK 〉 K2CO3. Especially, the addition of KCI significantly improved the catalytic activities of PdCl2-CuCl2/AC catalyst for DMC synthesis from CO and MN. N2 adsorption data indicated that the addition of K promoters did not change the textural properties of Wacker-type catalysts greatly. H2-TPR and XPS results demonstrated that the existence of KCI promoted the reducibility of Cu2＋ species and increased the proportion of Cu2＋ species on catalyst surface, which is favorable for oxidizing Pd0 to active Pd2＋. Further, the addition of KCI benefited the reactivity of PdCI2- CuCl2/AC catalwt for DMC synthesis from CO and MN.

An in situ infrared study of dimethyl carbonate synthesis from carbon dioxide and methanol over well-shaped CeO2

The mechanism of dimethyl carbonate（DMC） formation from CO2 and methanol is investigated using three well-shaped CeO2 catalysts, nanorod, nanocube and octahedron, which are packed with different crystal planes. In situ Fourier Transform Infrared Spectroscopy（FTIR） is employed to probe each reaction step in the DMC synthesis. The number of –OH groups and the species of CO2 adsorptions on ceria surface have significant influence on the activity of ceria with different morphologies. Rod-ceria has favorable catalytic activity because of the large amount of –OH groups and the formation of bidentate carbonate species.

Highly active Pd-Fe/α-Al_(2)O_(3) catalyst with the bayberry tannin as chelating promoter for CO oxidative coupling to diethyl oxalate

A novel Pd-Fe/α-Al_(2)O_(3) catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring a-Al_(2)O_(3) as support for the synthesis of diethyl oxalate from CO and ethyl nitrite.A variety of characterization techniques including N2 physical adsorption,optical microscopy,scanning electron microscopy and energy dispersive system(SEM-EDS),inductively coupled plasma optical emission spectroscopy(ICP-OES),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),were employed to explore the relationship between the physicochemical properties and activity of catalysts.It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd,reduce the particle size and make the active Pd as a multi-ring distribution on the commercial a-Al2O3 suppo rt,which we re beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite.0.3 wts Pd-Fe/α-Al_(2)O_(3) showed excelle nt catalytic activity and selectivity in a continuous flow,fixed-bed reactor with the loading amount of 10 mL catalysts,Under the mild reaction conditions,the space-time yield of diethyl oxalate was 978 g L^(-1) h^(-1) and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.

Enhancements of dimethyl carbonate synthesis from methanol and carbon dioxide:The in situ hydrolysis of 2-cyanopyridine and crystal face effect of ceria

This paper describes the effect of the in situ hydrolysis of 2-cyanopyridine and its derivatives on the synthesis of dimethyl carbonate（DMC） from CO2 and methanol over CeO2.2-Cyanopyridine.with the highest electronic charge number of the carbon in the cyanogroup,is the most effective agent to accelerate the desired reaction by a decrease of water.CeO2（110） planes are active for the hydrolysis of 2-cyanopyridine,further enhancing the DMC formation by in situ removal of water effectively.The DMC yield is improved drastically up to 378.5 mmol g cat^-1 from 12.8 mmol g cat^-1 with the in situ hydrolysis of 2-cyanopyridine over rod-CeO2（1 1 0） catalyst.