catalytic effect
Recently Published Documents


TOTAL DOCUMENTS

1963
(FIVE YEARS 519)

H-INDEX

59
(FIVE YEARS 23)

Fuel ◽  
2022 ◽  
Vol 312 ◽  
pp. 123002
Author(s):  
Nail R. Khafizov ◽  
Timur I. Madzhidov ◽  
Chengdong Yuan ◽  
Mikhail A. Varfolomeev ◽  
Oleg N. Kadkin

2022 ◽  
Author(s):  
Timothy Wilson ◽  
Mark Eberhart

Bond bundles are chemical bonding regions, analogous to Bader atoms, uniquely defined according to the topology of the gradient bundle condensed charge density, itself obtained by a process of infinitesimal partitioning of the three-dimensional charge density into differential zero-flux surface bounded regions. Here we use bond bundle analysis to investigate the response of the charge density to an oriented electric field in general, and the catalytic effect of such a field on Diels-Alder reactions in particular, which in this case is found to catalyze by allowing the transition state valance bond bundle configuration to be achieved earlier along the reaction pathway. Using precise numerical values, we arrive at the conclusion that chemical reactions and electric field catalysis can be understood in terms of intra-atomic charge density redistribution, i.e., that charge shifts within more so than between atoms account for the making and breaking of bonds.


RSC Advances ◽  
2022 ◽  
Vol 12 (3) ◽  
pp. 1628-1637
Author(s):  
Gang Yang ◽  
Rui Ma ◽  
Shifan Zhang ◽  
Ziying Liu ◽  
Dexuan Pei ◽  
...  

For the composite catalyst, there existed synergetic catalytic effect between the hydroxyl groups and the metal center. All chain growth simultaneously proceeded between the layers or on the surface of HNTs, conducting the in situ ROP.


Fuel ◽  
2022 ◽  
Vol 307 ◽  
pp. 121881
Author(s):  
Xiaodan Bao ◽  
Zhongjie Shen ◽  
Haigang Zhang ◽  
Qinfeng Liang ◽  
Haifeng Liu

2021 ◽  
Author(s):  
Timothy Wilson ◽  
Mark Eberhart

Bond bundles are chemical bonding regions, analogous to Bader atoms, uniquely defined according to the topology of the gradient bundle condensed charge density, itself obtained by a process of infinitesimal partitioning of the three-dimensional charge density into differential zero-flux surface bounded regions. Here we use bond bundle analysis to investigate the response of the charge density to an oriented electric field in general, and the catalytic effect of such a field on Diels-Alder reactions in particular, which in this case is found to catalyze by allowing the transition state valance bond bundle configuration to be achieved earlier along the reaction pathway. Using precise numerical values, we arrive at the conclusion that chemical reactions and electric field catalysis can be understood in terms of intra-atomic charge density redistribution, i.e., that charge shifts within more so than between atoms account for the making and breaking of bonds.


2021 ◽  
Vol 6 (3(62)) ◽  
pp. 6-10
Author(s):  
Ivan Zezekalo ◽  
Viktor Kovalenko ◽  
Iryna Lartseva ◽  
Olexandr Dubyna

The object of research is the catalytic effect (hydrocracking) for the production of hard-to-recover hydrocarbons, the subject of the study is the change in the physicochemical properties of hydrocarbons by partial gasification, and the lightening of the fractional composition of hydrocarbons. One of the most problematic areas is the lack of studies of the catalytic effect on hard-to-recover hydrocarbons in reservoir conditions. Although processes such as catalytic cracking, reforming, isomerization, aromatization and alkylation of hydrocarbons are known and used in petroleum refining. The research used the methods of scientific knowledge – experiment and measurement. In the course of laboratory work, an effective catalyst was developed, the effect of temperature on the fractional composition and physicochemical properties of oil, oil products and gas condensate was investigated. To simulate formation conditions, hermetic metal retorts were used, in which oil and gas condensate samples were subjected to different temperature regimes. In the process of testing cores saturated with gas condensate, the dependence of filtration on physical parameters – temperature and pressure, fractional composition, specific gravity and viscosity was studied. Laboratory studies have shown a decrease in density and viscosity of hydrocarbons, an increase in core permeability. The effect of catalysis on oil made it possible to increase the volume of light ends distillation from 30 to 60 %, for gas condensate – up to 50 %, which confirms the effectiveness of the method of catalysis of hard-to-recover hydrocarbons. This is due to the fact that the correct formulation and solution of the problem provided adequate results. In contrast to the existing processes of hydrocracking of petroleum products, the proposed method allows you to extract heavy and low-mobile hydrocarbons in reservoir conditions at lower temperatures of 120–150 °С. At the same time, the technology for catalytic hydrogenation of hard-to-recover hydrocarbons will be similar to a typical treatment of a formation with an acid or surfactants. This will make it possible to intensify the commercial reserves of hydrocarbons in the fields that are now classified as hard-to-recover and which account for more than 50 %.


Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2279
Author(s):  
Alena Shumskaya ◽  
Larissa Panina ◽  
Alexander Rogachev ◽  
Zhanna Ihnatovich ◽  
Artem Kozlovskiy ◽  
...  

Ni nanotubes (NTs) were produced by the template method in the pores of ion-track membranes and then were successfully functionalized with gold nanoparticles ([email protected] NTs) using electroless wet-chemical deposition with the aim to demonstrate their high catalytic activity. The fabricated NTs were characterized using a variety of techniques in order to determine their morphology and dimensions, crystalline structure, and magnetic properties. The morphology of Au coating depended on the concentration of gold chloride aqueous solution used for Au deposition. The catalytic activity was evaluated by a model reaction of the reduction of 4-nitrophenol by borohydride ions in the presence of Ni and [email protected] NTs. The reaction was monitored spectrophotometrically in real time by detecting the decrease in the absorption peaks. It was found that gold coating with needle-like structure formed at a higher Au-ions concentration had the strongest catalytic effect, while bare Ni NTs had little effect. The presence of a magnetic core allowed the extraction of the catalyst with the help of a magnetic field for reusable applications.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7696
Author(s):  
Tingting Lv ◽  
Luyao Kou ◽  
Tu Hu ◽  
Libo Zhang ◽  
Li Yang

We study the specific catalytic effect of the catalyst on the combustion process of pulverized coal of increasing the proportion of semicoke in the mixture of semicoke and bituminous coal, and reducing the cost of blast-furnace coal injection. A combination of thermogravimetric and kinetic analyses were used to study the catalytic effect of Fe2O3 on semicoke and bituminous coal, and to improve the amount of semicoke in the mixed coal powder of bituminous coal and semicoke. Experimental results showed that Fe2O3 had a catalytic effect on both semicoke and bituminous coal, but there were differences in the catalytic stages of the same catalyst for different pulverized coal types. The addition of 2 wt % Fe2O3 to semicoke and bituminous coal each led to the ignition temperature and maximal burning rate temperature of the semicoke decreasing, indicating that the catalyst promoted the precipitation of a volatile fraction from the semicoke. The maximal burning rate temperature and burnout temperature of the bituminous coal decreased, and maximal weight loss rate increased, indicating that the catalyst promoted the combustion of the fixed carbon of bituminous coal. The optimal proportioning amount of semicoke in the mixed coal powder without the addition of a catalyst was 25%. After adding 2 wt % Fe2O3, the proportional amount of semicoke increased by 10%. The addition of the catalyst resulted in even lower activation energy for the same conversion rate. When the conversion rate was in the ranges of 0.1–0.2 and 0.5–0.7, the activation energy decreased by 22% and 26%, respectively, compared with that without a catalyst. Fe2O3 promoted the combustion of bituminous coal and semicoke. This enhanced the combustion performance of the pulverized coal mix and increased the proportion of semicoke in the mix, which has certain guiding significance in reducing the cost of blast-furnace iron making.


Author(s):  
Haoming Chen ◽  
Tianle Li ◽  
Zhiming Xu ◽  
Wenju Wang ◽  
Haihou Wang

Abstract Diesel engine has attracted much attention because of its good power performance, fuel economy, reliability and durability, but the exhaust gas containing soot has a great impact on the environment and human health. Catalyzed diesel particulate filter (CDPF) that reduces the activation energy of soot oxidation and combustion by catalysts are used to eliminate soot. In this paper, MFe2O4 spinel (M=Cu, Ni and Co) was synthesized by sol-gel method to catalyze the combustion of soot. The Characterization results of MFe2O4 showed that CuFe2O4 possessed the smallest average grain size (65.6nm) and the best redox performance. The activity test of the catalyst shows that the activity order of the catalyst is CuFe2O4 (330 °C > CoFe2O4 (411 °C > NiFe2O4 (464 °C). DFT results showed that carbon is more easily adsorbed on the oxygen-terminal surface of CuFe2O4 and reacts with oxygen vacancies, resulting in the promotion of soot oxidation by the diffusion of oxygen from the inside to the surface. It also proves that CuFe2O4 has the best catalytic effect on soot.


Sign in / Sign up

Export Citation Format

Share Document