by Luiz Felipe da M. Rocha  , Leonardo C. Ferreira  , Maria de Fatima V. Marques  , Rodrigo S. Bitzer  and Marco Antônio Chaer Nascimento

Received: 18 May 2022;  Published: 06 July 2022;  doi: 10.21926/cr.2203020

We synthesized and spectroscopically characterized a new heterotrimetallic {Ti2Ni} ethylene (co)polymerization precatalyst containing one (α-diimine)NiBr2 and two (phenoxy-imine)TiCl4 scaffolds. Its calculated structure was investigated at the DFT B3LYP/LACVP** level. Our calculations showed that the titanium(IV) centers were in a slightly distorted trigonal bipyramidal environment, and the average Ti···Ni distance was 8.76 Å. The precatalyst was used for synthesizing polyethylene and ethylene copolymers. The resul [...]

by Galina Huseynova  , Gulbeniz Мuхtаrоvа  , Nushaba Aliyeva  , Gular Gаsimоvа  and Sanubar Rаshidоvа

Received: 05 May 2022;  Published: 05 July 2022;  doi: 10.21926/cr.2203019

This article provides an overview of zeolite-containing catalysts used in the alkylation of benzene and toluene with olefins, isobutane with butenes and butane-butene fractions, gasoline and oil fractions with olefins, propane-propylene, and butane-butylene fractions of catalytic cracking. Zeolites have various types of structures, including BEA, MFI, MWW, FAU, etc., which differ in pore size and the number and location of the channels. High-silica zeolites have a large pore volume, high acidity, good hydrothermal [...]

by Jiarui Fang  , Ziheng Li  , Xiruo Bai  , Yichu Zhang  , Jiahui Liu  , Dan Wang  and Ye Yao

Received: 10 May 2022;  Published: 04 July 2022;  doi: 10.21926/cr.2203018

TiO2 (001) crystal plane exhibits molecular adsorption and photocatalytic activity. The loading capacity of reactive oxygen species present on crystal planes helps in the significant improvement of catalytic activity. The methods of synthesis and conditions of existence significantly affect the molecular adsorption properties of crystal planes, which in turn affects the ability of the system to load reactive oxygen species. Herein, we report the simulation of the molecular adsorption behavior on the TiO2 (001) usin [...]

by Sabira Sabir Ismayilova  and Sabir Qarsh Amirov

Received: 09 January 2022;  Published: 28 June 2022;  doi: 10.21926/cr.2202017

The kinetics of dearomatization of a kerosene fraction processed using a zeolite catalyst (0.9 HZSM-5) at different temperatures (160-200°C), the molar ratio between the aromatic hydrocarbons present in the kerosene fraction and n-decene (1:(0.5-4)), and the reaction time (1-3 h) were studied. Based on the obtained data, a kinetic model for kerosene dearomatization is proposed. It is assumed that the single-center Riedel mechanism is followed. The stage associated with the interaction between n-decene adsorbed on t [...]

by Jia Yu  , Haiyan Jing  , Zongdeng Wu  , Boyuan Liu  , Wu Lei  and Qingli Hao

Received: 29 April 2022;  Published: 21 June 2022;  doi: 10.21926/cr.2202016

The rational design of efficient electrocatalysts for oxygen reduction reaction (ORR) is the key to developing fuel cells and metal-air batteries. Carbon-supported iron-based materials, as the most promising electrocatalysts for ORR, have drawn much attention as they are cost-effective and exhibit high activity. In this work, a three-dimensional (3D) Fe3O4-decorated N-doped graphene aerogel (Fe3O4/NGA) catalyst was synthesized following a simple hydrothermal method which was followed by an annealing process. The co [...]

by Hiromi Matsuhashi

Received: 28 April 2022;  Published: 06 June 2022;  doi: 10.21926/cr.2202015

Solid base catalysts consisting of MgO modified with 10 mol% ZnO (ZnO/MgO) were prepared by depositing zinc(II) acetylacetonate (Zn(acac)2) in polar and nonpolar organic solvents on the surface of MgO and Mg(OH)2. The process was followed by thermal decomposition in air at 773 K over a period of 3 h. The activity of MgO modified with Zn(acac)2 for base-catalyzed retroaldol reaction (the decomposition of diacetone alcohol (4-hydroxy-4-methyl-2-pentanone) to acetone) at 299 K was higher than the activity of unmodifie [...]

by Pan Xie  , Dongdong Du  , Cheng Xue  and Sanshan Shi

Received: 01 April 2022;  Published: 10 May 2022;  doi: 10.21926/cr.2202014

The process of light-induced C-H oxygenation is of high interest as it can be used for the construction of oxygenated compounds. Herein, we report a mild and general method for the efficient synthesis of aromatic ketones following the process of metal-free C-H oxygenation. With air as the oxidant, high functional tolerance was demonstrated, and the desired ketones were obtained in moderate to excellent yields at room temperature (25 oC). Mechanistic studies suggested that the oxidative transformation potentially oc [...]

by Joelise A.F. de Alencar Figueira Angelotti  , Daniela B. Battaglia Hirata  and Myllena R. Rodrigues dos Santos

Received: 16 February 2022;  Published: 07 May 2022;  doi: 10.21926/cr.2202013

Enzymes are extensively used in biotechnological processes in several areas of industry. They are sustainable and safe, and their specificity is another characteristic that improves the performance in the process. Among enzymes, lipase is relevant due to the ability to play different roles in the industry and the possibility of collecting them from microbial sources that are found in industrial residues. This can reduce the costs of enzyme production. In relation to that, lipase immobilization is an interesting pro [...]

by Shangkun Deng  , Yini Lei  , Yiyu Deng  , Yilan Lai  and Xingyuan Gao

Received: 29 January 2022;  Published: 26 April 2022;  doi: 10.21926/cr.2202012

The use of the dry reforming of methane (DRM) to convert the two principal greenhouse gases, methane and carbon dioxide, to syngas (a mixture of H2 and CO) has attracted increasing attention in recent years. However, the DRM reaction suffers from the twin disadvantages of carbon deposition and sintering, so a highly efficient and robust catalyst with superior anti-deactivation properties is required. One way to meet this need is to incorporate active metals into crystalline oxides, such as perovskite. In this paper [...]

by Mouhamad Rachini  , Mira Jaafar  , Fatima Al Ali  , Zahraa Slaiman  , Mohamad Kassem  , Eugene Bychkov  , T. Jean Daou  , Joumana Toufaily  and Tayssir Hamieh

Received: 29 January 2022;  Published: 21 April 2022;  doi: 10.21926/cr.2202011

The use of Pd-Cu bimetallic catalysts in the reduction of aqueous nitrate ions by hydrogen was studied. The catalysts were supported on multi-walled carbon nanotubes (MWCNTs), activated carbon (AC), and Titania, and the influence of the support on the nitrate reduction activity in water was then investigated. The catalysts were characterized before and after use by FT-IR, XRD, SEM, EDX, and Laser Granulometry. It was found that the surface characteristics of the support have an influence on the catalyst activity, w [...]