Kinetic Study of Oxidative Dehydrogenation of Ethane over MoVTeNb Mixed-Oxide Catalyst

Optimization of the catalytic production of methyl stearate by applying response surface Box-Behnken design: an intensified green option for high-cetane biofuel manufacture

To enhance the efficiency of processes by decreasing the reaction severity and energy consumption, and reducing the equipment size, facilities' space and operation cost, process intensification is an increasingly used option in the chemical industry. Within this framework and in agreement with some of the green chemistry principles (design for energy efficiency and use of renewable feedstocks), this work deals with the implementation of high-shear mixing (HSM) to intensify the homogeneous esterification of stearic acid (SA) with methanol to methyl stearate, a high-cetane number alkyl ester suitable to be added into biofuel streams. The response surface Box-Behnken design (BBD) is applied to quantify the main effects and two-way interactions of four key input reaction factors: methanol : SA ratio (7-16 mol mol-1), catalyst mass (0.25-4.0 wt%), temperature (40-60 °C), time (1-12 min), and to approximate the optimal conditions on the intensified SA esterification. The statistical BBD results indicates that the four linear effects, two of the four possible quadratic effects (catalyst mass and temperature) and only one (catalyst mass-time) of the six existing two-way interactions are statistically relevant at the 95% confidence level. Catalyst mass is the most influencing factor in the reaction, followed by methanol : SA ratio, temperature, and time. The proposed second-order regression model predicts that the intensified esterification requires only 12 min to practically convert all SA (99% ± 6.8%) running the reaction at 12.4 methanol : SA ratio, 4 wt% catalyst mass, 60 °C and 500 rpm, a value experimentally validated (93.2% ± 0.7%). Under these conditions and with the assistance of HSM, the typical reaction length of conventional heterogeneous and homogeneous-phase esterification processes decreases from 5 to 117 and 35 to 90 times, respectively.

State-of-the-Art Review of Oxidative Dehydrogenation of Ethane to Ethylene over MoVNbTeOx Catalysts

Ethylene is mainly produced by steam cracking of naphtha or light alkanes in the current petrochemical industry. However, the high-temperature operation results in high energy demands, high cost of gas separation, and huge CO2 emissions. With the growth of the verified shale gas reserves, oxidative dehydrogenation of ethane (ODHE) becomes a promising process to convert ethane from underutilized shale gas reserves to ethylene at a moderate reaction temperature. Among the catalysts for ODHE, MoVNbTeOx mixed oxide has exhibited superior catalytic performance in terms of ethane conversion, ethylene selectivity, and/or yield. Accordingly, the process design is compact, and the economic evaluation is more favorable in comparison to the mature steam cracking processes. This paper aims to provide a state-of-the-art review on the application of MoVNbTeOx catalysts in the ODHE process, involving the origin of MoVNbTeOx, (post-) treatment of the catalyst, material characterization, reaction mechanism, and evaluation as well as the reactor design, providing a comprehensive overview of M1 MoVNbTeOx catalysts for the oxidative dehydrogenation of ethane, thus contributing to the understanding and development of the ODHE process based on MoVNbTeOx catalysts.

Phase-pure M1 MoVNbTeOx/TiO2 nanocomposite catalysts: high catalytic performance for oxidative dehydrogenation of ethane

The introduction of TiO2 can improve the catalytic performance of phase-pure M1 MoVNbTeOx in the ODHE process, in which the STY enhancement of M1/40TiO2 at 400 °C and W/F = 7.55 gcat h molC2H6−1 reached ∼76%.

Unravelling the redox mechanism and kinetics of a highly active and selective Ni-based material for the oxidative dehydrogenation of ethane

Bridging the gap between catalysis and reaction engineering during the kinetic analysis of the oxidative dehydrogenation of ethane over a highly active and selective Ni-based material.

Oxidative dehydrogenation of ethane: catalytic and mechanistic aspects and future trends

Ethane oxidative dehydrogenation (ODH) is an attractive, low energy, alternative route to reduce the carbon footprint for ethene production, however, the commercial implementation of ODH processes requires catalysts with improved selectivity.

Mars van Krevelen Mechanism for the Selective Partial Oxidation of Ethane

Ethylene is the most important olefin in the petrochemical context, since it is the main raw material for the production of many polymers. Traditional production of ethylene via thermal cracking and catalytic dehydrogenation consumes large amounts of energy; hence selective partial oxidation of ethane has been considered as an attractive alternative production path. Recently, development of a promising catalyst for selective partial oxidation of ethane, which consists of multi-metallic mixed oxides of Mo, Te, V, and Nb, has been published. It is also noteworthy that this catalytic system starts to be active at temperatures below 400 °C, substantially lower than the one required by commercial thermal processes, >800 °C. In this work, a kinetic mechanism based on Mars van Krevelen formalism is proposed for the selective partial oxidation of ethane, considering the surface itself as active protagonist of the reaction. RedOx steps on active sites are considered as the controlling ones, and the rest of transformations are considered as pseudo-steady steps. It is noticed that there are side reactions, which produces CO and CO2 as combustion by-products. Additionally, there is competition for reduced sites on the catalytic surface, mainly between oxygen and water molecules, which adsorb strongly on these sites. Adjusted results by the mechanism proposed are in agreement with experimental observations of reaction rates diminishing proportionally to partial pressure of water, caused by competition of reduced sites on catalyst surface.

Statistically Guided Synthesis of MoV-Based Mixed-Oxide Catalysts for Ethane Partial Oxidation

The catalytic performance of Mo8V2Nb1-based mixed-oxide catalysts for ethane partial oxidation is highly sensitive to the doping of elements with redox and acid functionality. Specifically, control over product distributions to ethylene and acetic acid can be afforded via the specific pairing of redox elements (Pd, Ni, Ti) and acid elements (K, Cs, Te) and the levels at which these elements are doped. The redox element, acid element, redox/acid ratio, and dopant/host ratio were investigated using a three-level, four-factor factorial screening design to establish relationships between catalyst composition, structure, and product distribution for ethane partial oxidation. Results show that the balance between redox and acid functionality and overall dopant level is important for maximizing the formation of each product while maintaining the structural integrity of the host metal oxide. Overall, ethylene yield was maximized for a Mo8V2Nb1Ni0.0025Te0.5 composition, while acetic acid yield was maximized for a Mo8V2Nb1Ti0.005Te1 catalyst.

Shale Gas Implications for C2-C3 Olefin Production: Incumbent and Future Technology

Substantial natural gas liquids recovery from tight shale formations has produced a significant boon for the US chemical industry. As fracking technology improves, shale liquids may represent the same for other geographies. As with any major industry disruption, the advent of shale resources permits both the chemical industry and the community an excellent opportunity to have open, foundational discussions on how both public and private institutions should research, develop, and utilize these resources most sustainably. This review summarizes current chemical industry processes that use ethane and propane from shale gas liquids to produce the two primary chemical olefins of the industry: ethylene and propylene. It also discusses simplified techno-economics related to olefins production from an industry perspective, attempting to provide a mutually beneficial context in which to discuss the next generation of sustainable olefin process development.

Production of Ethylene and its Commercial Importance in the Global Market

Ethylene is the largest of the olefin markets and is also one of the most important petrochemically derived monomers that are used as a feedstock for the production of various commercially useful chemical products (e.g. polyethylene, polymers, fibers etc.). The primary objective of this chapter is to provide a comprehensive overview about olefins particularly ethylene production technologies and its commercial significance in the world market. The content of this chapter is presented as follows: a general overview about olefins production is given. This is followed by introducing the reader to ethylene including its properties importance/applications. The next section describes the production technologies of ethylene and some of its selected derivatives, followed by an overview of the technology, market, costs, capacity, global demand and supply of ethylene technology. Finally, main points and outlook of this highly industrially important commodity chemical are summarized.