Silver catalysts for ethylene epoxidation

High surface area α-aluminas III. Oxidation of ethylene, ethylene oxide, and acetaldehyde over silver dispersed on high surface area α-alumina

Kinetic hydrogen isotope effects in ethylene oxidation on silver catalysts

This research has been performed in the Ethylene Oxide production process. It is a flammable and colorless gas at temperatures above 11 °C. It is an important commodity chemical for the production of solvents, antifreeze, textiles, detergents, adhesives, polyurethane foam, and pharmaceuticals. Small amounts of Ethylene Oxide [EO] are used in manufacturing fumigants and sterilants for spices and cosmetics, as well as hospital sterilization for surgical equipment. Modern Ethylene oxide [EO] productions employ either air or oxygen (O2)to oxidize ethylene (C2H4) with a silver catalyst on an alumina oxide carrier[Ag/Al2O3]catalyst packed in a fixed-bed reactor (plug-flow reactor)but the oxygen-base reaction process is more desirable here we used oxygen. Mainly two reactions occur, partial oxidation of ethylene to ethylene oxide and total oxidation of ethylene to carbon dioxide and water. The design models of the process in this research based on a three-part system. They are: the reaction system, absorption system and Ethylene Oxide [EO] purification system. The largest cost in production of ethylene oxide is ethylene therefore, it’s important to optimize the selectivity towards ethylene oxide and thus reduce the consumption of Ethylene. The aim of this work is to create a simulation model of the Ethylene Oxide production process from Ethylene using Aspen Hysys V9. Also to knowing the optimum operational conditions (temperature –pressure –flow rate) for the oxidation reactions of Ethylene. The simulation was running three times with various operational conditions to make a good result. The conclusion was that during operational time the activation energy increased for both reactions which have to be compensated with increasing reactor temperature. At the same time the selectivity for producing Ethylene Oxide decreases, i.e. more carbon dioxide and water are formed. The simulation models yield Ethylene Oxide with purity of 99.2%.

This article is devoted to the consideration of methods for the industrial production of ethylene oxide. Ethylene oxide is produced in large quantities and is primarily used as an intermediate in the production of a number of industrial chemicals, the best known of which is ethylene glycol. The process of producing ethylene oxide is carried out by a direct vapor-phase oxidation process, in which ethylene is oxidized to ethylene oxide by air or oxygen and a silver catalyst at 10-30 atm (1–3 MPa) and 200-300 °C. Ethylene oxidation can be carried out in several ways: air, oxygen under nitrogen ballast, oxygen under methane ballast. The production of ethylene oxide is one of the most dynamically developing. In Russia, the leading place in the production of ethylene oxide is occupied by the enterprise PJSC Nizhnekamskniftekhim. In 2012, the installation for producing ethylene oxide was reconstructed. The reconstruction consisted of transferring the ethylene oxide synthesis stage to methane ballast conditions. A patent analysis was carried out to determine the relevance of this process.

A pair of 2-[(n-methylcyclohexyl)methyl]piperidine (H12-MBP) and its full dehydrogenation product (H0-MBP) has recently been considered as a potential liquid organic hydrogen carrier with 6.15 wt% H2 storage capacity. In the discovery of an active and stable catalyst for H2 discharge from H12-MBP at lower temperatures, a mesoporous Pd-Al2O3 catalyst (MPdA) was synthesized by a one-pot solvent deficient precipitation (SDP). In the present work, the sensitivity and effectiveness of the SDP method are examined by varying the calcination temperature and time in the preparation of the MPdA catalyst. The characterization revealed that the final properties of the MPdA catalyst greatly rely on both the calcination temperature and time. The MPdA catalyst showed better dehydrogenation activity for calcination at 600 °C than at other temperatures, because of Pd particles of smaller size with higher dispersion. Although the MPdA catalysts calcined at 600 °C for different periods of time have similar size and dispersion of Pd particles, the dehydrogenation efficiency was superior as the calcination time became shorter (e.g., 1 h), which originated from the better arrangement of Pd particles over a higher surface area. These MPdA catalysts, irrespective of the calcination time, displayed a remarkable stability in the dehydrogenation of H12-MBP owing to the protection of Pd particles by the Al2O3 layer.

Addition of rhenium (Re) to Pt-Ru/f-MWCNT anode electrocatalysts for enhancement of ethanol electrooxidation in half cell and single direct ethanol fuel cell

Supported silver catalysts for the oxidation of ethylene: The effects of thermal treatment of alumina as catalyst support

Cage-like mesoporous organosilicas with isocyanurate bridging groups synthesized by soft templating with poly(ethylene oxide)–poly(butylene oxide)–poly(ethylene oxide) block copolymer

Synthesis of Highly Efficient WO<sub>3</sub>-Doped MCF Catalyst and Its Application in the Selective Oxidation of Cyclopentene to Glutaraldehyde

A reaction mechanism for the silver catalyzed oxidation of C2H4 by oxygen has been formulated which is consistent with kinetic data for this system. It is suggested that both ethylene oxide and CO2 formation involve interaction of single gaseous C2H4 molecules with single oxygen adatoms. This may be a system of two parallel reactions of different activation energy requirements or a common initiation step to form adsorbed ethylene oxide which may then desorb immediately or isomerize to acetaldehyde followed by rapid oxidation to CO2 and H2O. Account is taken of the known adsorption characteristics of O2 on silver to deduce expressions for initial rates of ethylene oxide and CO2 formation as a function of reactant partial pressures. The generalized form of the equation is r = k(1 + a/pE + b/pO)−1, where k, a, and b are temperature dependent constants and pE and pO are partial pressures of ethylene and of oxygen respectively.A mechanism is also suggested for the heterogeneous oxidation of ethylene oxide which involves interaction between a gas phase ethylene oxide molecule and a single oxygen adatom to form an intermediate (probably formaldehyde) which is rapidly oxidized to CO2 and H2O. A similar expression to that above for the initial oxidation rate is deduced. These expressions have been fitted successfully to experimental data.

Colloidal silver catalysts for oxidation of ethylene

Epoxidation of ethylene by anion radicals of α-oxygen on the surface of FeZSM-5 zeolite

The effectiveness of MoV(Nb,Ta)(Te,Sb)O catalysts for the selective oxidation of propane to acrylic acid (AA) and ammoxidation to acrylonitrile (AN) is well known and recorded in the literature. One of the best known catalyst systems is comprised of two phases: M1 (orthorhombic) Mo7.8V1.2NbTe0.94O28.9 and M2 (pseudo-hexagonal) Mo4.67V1.33Te1.82O19.82, usually in a 60/40 ratio. The M1 structure performs all of the catalytic functions needed for converting propane to acrylic acid or acrylonitrile, since all key metals having the desired catalytic functions are located at the active center of the catalyst and within bonding distance of each other to perform this complex task. The M2 phase is a co-catalyst in symbiosis with M1, performing a mop-up operation converting free intermediately formed propylene to the respective desired end products (AA or AN). Various attempts have been reported in the literature, with varying degrees of success, to substitute select elements of the two respective structures to enhance the yields of the desired end products. A yield improvement in either phase should theoretically lead to an enhancement of the overall desired yield and of M1/M2 optimal mixtures. Our current study concentrates on the selective doping of the M1, as well as, M2 structure in the selective oxidation of propane and propylene, respectively, to acrylic acid; it centers at doping these structures with low levels of elements having acidic (P, B, W) or redox (Cu) properties. Higher acrylic acid yields were obtained with the doped M1 (2–5%) and M2 (up to 15%) systems. Directed, high throughput methodology was employed as the experimental technique. The study of low doping levels is being extended to include a broader base of elements, as well as, M1/M2 mixtures (optimum compositions) aimed at achieving still higher useful product yields (AA or AN).

Optimization of media components for the production of N-acetylchitooligosaccharide from chitin by Streptomyces chilikensis through Taguchi experimental design

Epoxidation of ethylene over AgNaCl catalysts