Research Trends in Development of Highly Active Single Metal Oxide Catalyst for Oxidative Coupling of Methane

The conversion of methane to a value-added chemical is important for methane utilization and industrial demand for primary chemicals. Oxidative coupling of methane (OCM) to C2 hydrocarbons is one of the most attractive ways to use natural gas. However, it is difficult to obtain higher C2 yield in classic OCM reaction due to a favorable COx formation. Regarding this, various catalysts for OCM have been studied to fulfill desirable C2 yields. In this review, we briefly overview the single metal oxide types of OCM catalysts (alkaline-earth metal oxides and rare-earth metal oxides) and highlight the characteristics of catalysts in OCM reaction such as methane activation, surface basicity and lattice oxygen.

The Role of Alkaline/alkaline Earth Metal Oxides in CO2 Capture: A Concise Review

Reducing the concentration of CO2 from the atmosphere has attracted a lot of attention given the rapid level of industrialization in the world. Process Industries are one of the major contributors to this pollution in terms of the incessant release of CO2 from flue gas streams. In recent times metal oxides have received a lot of attention as potential adsorbents for solving this problem.They find application in post-, pre-, and oxy-combustion conditions. Their basic sites plus a lower charge to radius ratio increase their ionic nature and site basicity and facilitate the capture of this pernicious gas from flue gas streams by reacting to form carbonates, which when heated liberates an almost pure stream of CO2 which can be sequestered, thereby, aiding the release of environmentally benign flue gas streams to the atmosphere. This work takes a concise review of these metal oxides that have been widely studied.

CO2 capture using solid sorbents: Fundamental aspects, mechanistic insights and recent advances

Carbon dioxide capture and mitigation forms a key part of the technological response to combat climate change and reduce CO2 emissions. Solid materials capable of reversibly absorbing CO2 have been the focus of intense research for the past two decades, promising stability and low energy costs to implement and operate compared to the more widely used liquid amines. In this Review, we explore the fundamental aspects underpinning solid CO2 sorbents based on alkali and alkaline earth metal oxides operating at mid- to high temperature: how their structure, chemical composition and morphology impact their performance and long-term use. Various optimization strategies are outlined to improve upon the most promising materials, and we combine recent advances across disparate scientific disciplines including materials discovery, synthesis, and in situ characterization to present a coherent understanding of the mechanisms of CO2 absorption both at surfaces and within solid materials.

State of Art of Alkaline Earth Metal Oxides Catalysts Used in the Transesterification of Oils for Biodiesel Production

Biodiesel produced through catalytic transesterification of triglycerides from edible and non-edible oils and alcohol is considered an alternative to traditional petro-diesel. The interest in the use of alkaline earth metal oxides as heterogeneous basic catalysts has increased due to their availability, non-toxicity, the capacity to be reused, low cost, and high concentration of surface basic sites that provide the activity. This work is a compilation of the strategies to understand the effect of the source, synthesis, and thermal treatment of MgO, CaO, SrO, and BaO on the improvement of the surface basic sites density and strength, the morphology of the solid structure, stability during reaction and reusability. These parameters are commonly modified or enhanced by mixing these oxides or with alkaline metals. Also, the improvement of the acid-base properties and to avoid the lixiviation of catalysts can be achieved by supporting the alkaline earth metal oxides on another oxide. Additionally, the effect of the most relevant operation conditions in oil transesterification reactions such as methanol to oil ratio, temperature, agitation method, pressure, and catalysts concentration are reviewed. This review attempts to elucidate the optimum parameters of reaction and their application in different oils.

Increased hole mobility in anti-ThCr2Si2-type La2O2Bi co-sintered with alkaline earth metal oxides for oxygen intercalation and hole carrier doping

Metallic anti-ThCr2Si2-type RE2O2Bi (RE = rare earth) with Bi square nets show superconductivity while insulating La2O2Bi shows high hole mobility, by expanding the c-axis length through oxygen intercalation. In this...

Approaching Bulk from the Nanoscale: Extrapolation of Binding Energy from Rock-Salt Cuts of Alkaline Earth Metal Oxides

ABSTRACT A systematic DFT study is performed on (MgO)B, (CaO)n, (SrO)n, and (BaO)n clusters with 6 < n < 50, and which display a cuboid 2X2X2 atomic motif seen in the bulk, rock-salt, configuration. The stability and energy progression of these clusters are used to predict the energies of infinitely long nanorods, or nanowires, slabs, and the bulk global minimum energy. Keywords: Alkaline earth metal oxides, nanoclusters, nanorods, DFT.

Solution combustion synthesis of Ni/La2O3 for dry reforming of methane: tuning the basicity via alkali and alkaline earth metal oxide promoters

Alkali and alkaline earth metal oxides-promoted Ni/La2O3 catalysts synthesized by solution combustion synthesis revealed enhanced catalytic performance towards dry reforming of methane.

NON-PLASTIC RAW MATERIALS FOR THE PRODUCTION OF CONSTRUCTION CERAMICS

research by some scientists shows that the most expensive element in the manufacture of construction ceramics are clay materials, in particular kaolins. They allow getting products with high strength, but at the same time increase significantly the mass refractoriness. In this connection, a significant amount of melt is added or the firing temperature is increased. Of course, this leads to an increase in the cost of products. In Russia, the reserves of these raw materials are insufficient and it is advisable to look for new non-traditional types of raw materials. There is a need to adjust the component composition of ceramic masses and use non-plastic raw materials. An example is natural wollastonites or their analogues in the form of diopside, which are a little-used type of mineral raw material. In the Siberian region, there are several deposits of non-plastic varieties of raw materials for the production of fired construction products. The most famous are the deposits of the Slyudyansky and Sayan districts. The authors present the results of analysis of diopside rocks, where the chemical, mineral compositions and behavior of samples under heating are studied. The absence of alkali and alkaline earth metal oxides in diopsides was determined. The content of iron oxide in the amount of 0.1% indicates the purity of the raw material. More than half of the composition is occupied by silica, which is 53% and 58% in the rocks of the Burutuysky and Sayan deposits, respectively. The basis of the mineral composition of the samples is diopside, with the presence of quartz, calcite, mica and magnesium carbonate. This range of minerals is traditional in many charges of ceramic materials. Therefore, the possibility of using diopside rocks in the production of building ceramic materials is quite high.