Reaction kinetics

Bài giảng Xúc tác - Chương 4: Động học phản ứng xúc tác (Kinetics of catalytic reactions). Chương này cung cấp cho học viên những nội dung gồm: giới thiệu; nồng độ trên bề mặt của chất bị hấp phụ; các mô hình (model) phản ứng trên xúc tác rắn; cách xây dựng phương trình tốc độ;... Mời các bạn cùng tham khảo!

11p mothuahoa 04-05-2024 4 2   Download

C2H5OH has been using as an alternative fuel for decades; HO2 also plays a pivotal role in the combustion. The kinetics and mechanism for the reaction between C2H5OH and HO2 radical have been investigated using the molecular parameters for the reactants, transition states and products predicted at the CCSD(T)//B3LYP/6-311++G(3df,2p) level of theory.

7p tamynhan6 14-09-2020 16 1   Download

This study aims at better understanding the chemical and physico-chemical phenomena of uranium dioxide dissolution reactions in nitric acid media in the Purex process, which separates the reusable materials and the final wastes of the spent nuclear fuels.

13p christabelhuynh 29-05-2020 12 0   Download

Kinetic study of oxidation of toluidine blue (TB+) by periodate was carried out in aqueous medium and also in the cetyl trimethyl ammonium bromide (CTAB) reverse micellar medium. In both the media reaction obeys first order kinetics with respect to each of the reactants.

8p tocectocec 25-05-2020 7 1   Download

Objectives of thesis: Study on phenol treatment in water by ozonation process combined with catalysts. An empirical kinetic model and one quadratic regression equations were built based on experimental data for destroying phenol by heterogeneous catalytic ozonation process with response variables (initial pH, ozone concentration, catalyst concentration and reaction time). Application of phenol treatment in coking wastewater.

29p xacxuoc4321 08-07-2019 18 4   Download

A crucial turn in the investigation on NO decomposition occured when Iwamoto et al [1] first found that copper-exchanged zeolites, in particular Cu-ZSM-5 zeolites, were effective catalysts for NO decomposition. These catalysts have been the object of the most active investigations ever since. Due to small pore size of zeolites, the reactant diffusion seems play an important part in the reaction kinetics. This article is aimed to evaluate the role of diffusion by means of activation energy of NO decomposition on Me/Zeolites ZSM-5 and mordenit.

4p uocvong04 24-09-2015 47 5   Download

A crucial turn in the investigation on NO decomposition occured when Iwamoto et al [1] first found that copper-exchanged zeolites, in particular Cu-ZSM-5 zeolites, were effective catalysts for NO decomposition. These catalysts have been the object of the most active investigations ever since. Due to small pore size of zeolites, the reactant diffusion seems play an important part in the reaction kinetics. This article is aimed to evaluate the role of diffusion by means of activation energy of NO decomposition on Me/Zeolites ZSM-5 and mordenit.

3p uocvong04 24-09-2015 53 4   Download

Nanostructured Au-Ceria has been known as a promising catalyst for the low-temperature water-gas shisft reaction. The catalyst prepared by coprecipitation method with the gold loading various between 2 - 3 at.% with the crystallite size of 2.9 nm has been used to study some factors that effect to catalytic activity and long-term stability of this material.

5p uocvong04 24-09-2015 39 2   Download

Investigations of kinetics of p-xylene deep oxidation on CuO/ -Al2O3 and CuO/ZSM-5 have been carried out. Specific surface area and pore size of catalyst samples as well as metallic state characteristics and catalytic properties of copper have been established. Catalyst CuO/ZSM-5 has been found to be more active than the first one, but it expressed lower stability because of less stable active form of Cu2+ on zeolite surface.

6p uocvong03 24-09-2015 32 5   Download

The epoxy ester was prepared from epoxy resin DER 331 and fatty acid by esterification reaction in inert gas without catalyst. The kinetics of the esterification was investigated and the results shown that the temperature, reaction time and mol ratio of epoxy resin to fatty acid suitable to electro-deposition process are 220o C, 150 minutes and 1/4, respectively. The received epoxy ester was modified with 15% (wt%) maleic anhydride at 175o C for 120 min which was adapt to binder for anodic electro-deposition coating.

5p uocvong03 24-09-2015 51 5   Download

The photo catalytic efficiency of some TiO2 films (TiO2-ST01; TiO2-P25; TiO2 sol-gel) immobilized on glass has been investigated for the degradation of phenol in aqueous solution under UV light. It was shown that the best result obtained with TiO2-ST01 film, where the mineralization was the highest (70% TOC was removed after 3 hours of irradiations) and that related to the smaller particle size and the bigger surface areas of the TiO2-ST01 particles compared with TiO2-P25 and TiO2 sol-gel films. The effect of pH and phenol concentration were discussed.

6p uocvong02 24-09-2015 46 5   Download

Chemical doping nitrogen in to TiO2 crystal network by methods of sol-gel and impregnation was presented. The obtained nitrogen-doped TiO2 materials were characterized by different techniques such as XRD, SEM, UV-VIS. It was shown that samples have very uniform nano size, anatas structure and low level of band-gap energy (Ebg ~ 2.2 eV, ~ 500 - 600 nm). Their activity and kinetic were also studied and the results proved that in comparison with P25, the obtained nitrogen-doped TiO2 had higher activity and photo-quantum efficiency in organic disintegrated reaction under solar radiation.

6p uocvong01 24-09-2015 52 8   Download

Many biological C-H activation reactions exhibit nonclassical kinetic isotope effects (KIEs). These nonclassical KIEs are too large (kH/kD 7) and/or exhibit unusual temperature dependence such that the Arrhenius prefactor KIEs (AH/AD) fall outside of the semiclassical range near unity. The focus of this minireview is to discuss such KIEs within the context of the environmentally coupled hydrogen tunneling model.

9p system191 01-06-2013 37 4   Download

The gene fprA of Mycobacterium tuberculosis, encoding a putative protein with 40% identity to mammalian adrenodoxin reductase, was expressed in Escherichia coli and the protein purified to homogeneity. The 50-kDa protein monomer contained one tightly bound FAD, whose fluorescence was fully quenched. FprA showed a low ferric reductase activity, whereas it was very active as a NAD(P)H diaphorase with dyes. Kinetic parameters were determined and the specificity constant (kcat/Km) for NADPH was two orders of magnitude larger than that of NADH....

9p system191 01-06-2013 36 3   Download

Introducing site-directed mutations in surface-exposed residues of subunit II of the heme aa3 cytochrome c oxidase of Paracoccus denitrificans, we analyze the kinetic parameters of electron transfer from reduced horse heart cytochrome c. Specifically we address the following issues: (a) which residues on oxidase contribute to the docking site for cytochrome c, (b) is an aromatic side chain required for electron entry from cytochrome c, and (c) what is the molecular basis for the previously observed biphasic reaction kinetics....

9p system191 01-06-2013 36 3   Download

Microcalorimetry and UV-vis spectroscopy were used to conduct thermodynamic and kinetic investigations of the scission of calf thymus DNA catalyzed by bleomycin A5 (BLM-A5) in the presence of ferrous ion and oxygen. The molar reaction enthalpy for the cleavage, the Michaelis– Menten constant for calf thymus DNA and the turnover number of BLM-A5 were calculated by a novel thermokinetic method for an enzyme-catalyzed reaction to be )577 ± 19 kJÆmol)1, 20.4 ± 3.8 lM and 2.28 ± 0.49 · 10)2 s)1, respectively, at 37.0 °C. This DNA cleavage was a largely exothermic reaction....

9p system191 01-06-2013 31 4   Download

The involvement of the lysine residue present at the active site of Ehrlich ascites carcinoma (EAC) cell glyceraldehyde-3-phosphate dehydrogenase (Gra3P DH) was investigated by using the lysine specific reagents trinitrobenzenesulfonic acid (TNBS) and pyridoxal phosphate (PP). Both TNBS and PP inactivated EAC cell Gra3P DH with pseudo-first-order kinetics with the rate dependent on modifier concentration. Kinetic analysis, including a Tsou plot, indicated that both TNBS and PP apparently react with one lysine residue per enzyme molecule.

8p system191 01-06-2013 37 3   Download

The prokaryotic ATP-citrate lyase is considered to be a key enzyme of the carbon dioxide-fixing reductive tricarboxylic acid (RTCA) cycle. Kinetic examination of the ATP-citrate lyase from the green sulfur bacterium Chlorobium limicola (Cl-ACL), an a4b4 heteromeric enzyme, revealed that the enzyme displayed typical Michaelis-Menten kinetics toward ATP with an apparent Km value of 0.21 ± 0.04 mM. However, strong negative cooperativity was observed with respect to citrate binding, with a Hill coefficient (nH) of 0.45. ...

8p research12 01-06-2013 40 4   Download

A comparative study of thermodynamic and kinetic aspects of Cu(II) and Ni(II) binding at the N-terminal binding site of human and bovine serum albumins (HSA and BSA, respectively) and short peptide analogues was performed using potentiometry and spectroscopic techniques. It was found that while qualitative aspects of interaction (spectra and structures of complexes, order of reactions) could be reproduced, the quantitative parameters (stability and rate constants) could not.

9p research12 01-06-2013 38 4   Download

A gene having high sequence homology (45–49%) with the glycerol-1-phosphate dehydrogenase gene from Methanobacterium thermoautotrophicum was cloned from the aerobic hyperthermophilic archaeon Aeropyrum pernix K1 (JCM 9820). This gene expressed in Escherichia coli with the pET vector system consists of 1113 nucleotides with an ATG initiation codon and a TAG termination codon. The molecular mass of the purified enzyme was estimated to be 38 kDa by SDS/PAGE and 72.4 kDa by gel column chromatography, indicating presence as a dimer....

8p research12 01-06-2013 27 4   Download