Acetic acid decomposition on Pd(100) and Pd/Au(100) during vinyl acetate (VA) synthesis from ethylene acetoxylation is the primary source of such undesirable byproducts as methanol (CH3OH), acetaldehyde (CH3CHO), ketene (CH2CO), acetone (CH3COCH3), and methane (CH4), and also one possible source of surface carbon formation, which will lead to the deactivation of the catalyst. In this work, density functional theory (DFT) calculations and kinetic Monte Carlo (kMC) simulation were performed to probe the mechanism of acetic acid decomposition on Pd(100) and Pd/Au(100) at the molecular level. The corresponding adsorption of relevant species involved in acetic acid decomposition on Pd(100) and Pd/Au(100) was investigated, and the transition states of the elementary reactions involved were identified. The results show that the most probable pathway of acetic acid decomposition on Pd/Au(100) is CH3COOH → CH3COO+H → CO2+CH3+H → CO2+CH4, followed by CH3COOH → CH3COO+H → CO2+CH3+H → CO2+CH2+2H → CO2+CH+3H → CO2+C+4H, which agrees nicely with the results of many other researchers that CO2, CH4, H2 and surface carbon are the main products of acetic acid decomposition. If researchers can find some way to suppress the decarboxylation of CH3COO at the beginning in the future, then the overall undesirable byproducts can be further greatly reduced, which can significantly improve the quality of VA. Our work can provide guidance for designing and developing novel catalysts with high efficiency for VA synthesis from ethylene acetoxylation.

On the basis of Langmuir–Hinshelwood mechanism, with density functional theory method, all the dehydrogenation reactions in both Samanos mechanism and Moiseev mechanism in acetoxylation of ethylene to vinyl acetate, i.e., the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate (VAH), on Pd/Au(100) surface consisting of two diagonal Pd atoms were taken into consideration to examine the influence of surface oxygen atoms and hydroxyl groups on these dehydrogenation reactions. Besides, the corresponding adsorption of relevant species was investigated and the energetics of the dehydrogenation reactions was compared. Our calculations show that the surface Os kinetically facilitate ethylene dehydrogenation, but surface OHs kinetically inhibit ethylene dehydrogenation; the surface Os and OHs can kinetically facilitate acetic acid dehydrogenation, while they are kinetically unpreferable for VAH dehydrogenation; both surface Os and OHs are thermodynamically favored for the dehydrogenation of ethylene, acetic acid and VAH.

In this work, combined density functional theory (DFT) and experimental studies were conducted to investigate the structural, electronic and acidic properties of TiO2 nanoparticle supported on USY zeolite (TiO2/USY). DFT calculations suggest that there are mainly two interaction ways between TiO2 and USY zeolite, of which the bridge-form configuration appears more stable than the ring-form one. The bonding between TiO2 and USY zeolite was explored by analyzing the partial density of states to further understand the interactions. The acidity of TiO2/USY was evaluated by calculations of the deprotonation energy combined with TPD experiment. The results indicate that TiO2 modification changes the intensity distribution of the acid centers and induces the medium acid sites. The cracking reaction of model compound C10H12 verifies the remarkably improved cracking activity of TiO2/USY compared to the unmodified USY.

Laboratory wastewater has neither a regular discharge cycle nor a regular discharge quantity, and its compositions are so complex that they are rather difficult to dispose of. The purpose of this study is to set up a small laboratory wastewater treatment plant, and it mainly focuses on the treatment of organic wastewater in the laboratory via supercritical water oxidation (SCWO). The process conditions optimized experimentally were the following: 440 °C, 26 MPa, longer than 70 s of residence time, hydrogen peroxide as oxidant with a 2.6 times excessive rate. The reaction kinetics equation was obtained through study of the degradation reaction of laboratory wastewater in supercritical water. The wastewater treatment process was simulated with the program PRO/II, and a relatively complete design scheme of a laboratory wastewater treatment process by SCWO was proposed from such aspects as the mass balance, heat balance, and equipment calculation. At the same time, an equipment prototype was established, and thus, a small laboratory wastewater treatment plant could be set up.

This article is an up-to-date review of the literature available on the subject of ethanol to ethylene. The process of ethanol to ethylene has broad development prospects. Compared with the process of petroleum to ethylene, ethanol dehydration to ethylene is economically feasible. Researchers have been redirecting their interest to the ethylene production process, catalysts, and reaction mechanisms. A fluidized bed reactor, together with a wear-resistant, efficient, and stable catalyst will be the focus of future research that includes a deep understanding of the large-scale activated alumina catalyst and the molecular sieve catalyst used, and will promote the development of the ethanol dehydration to ethylene process and provide strong support for the market competiveness of the process.