Active carbon-supported nickel–palladium catalysts for hydrodechlorination of 1,2-dichloroethane and 1,1,2-trichloroethene

Pd-Ni bimetallic nanoparticles supported on TiO2 as an efficient catalyst for catalytic transfer hydrodeoxygenation of guaiacol

Bio-oil is a sustainable energy source, produced from pyrolysis of lignocellulosic materials or algae. It is, however, difficult to directly use the bio-oil for fuels due to several drawbacks, such as its viscosities and high oxygen content. One of the ways to solve this is upgrading of the bio-oil through hydrodeoxygenation (HDO). In this study, guaiacol was used as a bio-oil model compound in HDO reaction via catalytic transfer hydrogenation. The reaction was conducted in the presence of TiO2-supported palladium catalysts, with isopropyl alcohol as a hydrogen source. Nickel and Molybdenum were added into the Pd catalyst to investigate their effects on the catalyst activity. The prepared catalysts were characterized using XRD, N2-physisorption, H2-TPR, and TEM. HDO reaction was carried out using a pressurized batch reactor at 250 °C for 1 hour with 30 bar of He. Liquid products were analyzed by GC-MS and GC-FID to identify and quantify the conversions and product yields. The result showed that the presence of nickel on the catalyst could improve the catalytic activity of Pd/TiO2. Guaiacol conversion over Pd-Ni/TiO2 was 32.2%, while the conversion of guaiacol over Pd/TiO2 was only 17.9%. In addition, Pd-Ni/TiO2 showed good selectivity to produce cyclohexanol, while Pd/TiO2 showed good selectivity to produce one oxygenated compound such as 2-methylphenol and phenol.

Two Scenarios of Dechlorination of the Chlorinated Hydrocarbons over Nickel-Alumina Catalyst

Dechlorination processes attract great interest since they are involved in environmental protection and waste disposal technologies. In this paper, the process of gas-phase dechlorination of 1,2-dichloroethane, chloroform, and chlorobenzene over Ni/Al2O3 catalyst (90 wt% Ni) prepared by a coprecipitation technique was investigated. The reduction behavior of the oxide precursor NiO/Al2O3 was studied by thermogravimetric analysis in a hydrogen medium. A thermodynamic assessment of the conditions under which metallic nickel undergoes deactivation due to the formation of nickel chloride was performed. The dechlorination of chlorinated substrates was studied using a gravimetric flow-through system equipped with McBain balances in a wide range of temperatures (350–650 °C) and hydrogen concentrations (0–98 vol%). The impact of these parameters on selectivity towards the products of hydrodechlorination (C2H4, C2H6, and C6H6) and catalytic pyrolysis (carbon nanomaterial and CH4) was explored. The relationship between the mechanisms of the catalytic hydrodechlorination and the carbide cycle was discussed, and the specific reaction conditions for the implementation of both scenarios were revealed. According to the electron microscopy data, the carbonaceous products deposited on nickel particles during catalytic pyrolysis are represented by nanofibers with a disordered structure formed due to the peculiarity of the process including the side carbon methanation reaction.

A DFT study of chlorine coverage over late transition metals and its implication on 1,2-dichloroethane hydrodechlorination

Chlorine coverage and its impact on 1,2-dichloroethane hydrodechlorination over ten late transition metals, predicted using DFT-based phase diagrams.