Review on Alternative Route to Acrolein through Oxidative Coupling of Alcohols

Oxidative coupling of alcohols using methanol and ethanol, which can both be made renewable, is an attractive route to produce acrolein (propenaldehyde) in a single-step process. Currently acrolein is produced by direct oxidation of fossil propylene, and catalytic double dehydration of glycerol has been also investigated up to pilot scale. Although glycerol is an attractive feedstock, it suffers of several drawbacks. Addressing the limitations of both routes, the oxidative coupling of alcohols combines an exothermic oxidation and cross-aldolization. The best performing catalysts so far combine redox and acid/base sites. Reviewing the academic and patent literature, the present paper also addresses the economic analysis, to highlight the potential of this reaction at a yield from 70%, and at two different plant scales. The analysis has been made to guide further research, with the remaining technical problems to solve. Improved selectivity contributing to reduce the amount of equipment and the investment cost should be the prime target.

Thermally Intensification of Steam Reforming Process by Use of Methane Tri-Reforming: A Review

Tri- reforming is the main key for thermal intensification of hydrogen production based process. The arrangement of dry reforming, endothermic steam reforming, and exothermic partial oxidation make up a tri-reforming procedure. The benefit of the tri-reforming procedure is that it can be practical for energy supply for the dry and steam reforming reactions from the production of heat from the exothermic oxidation reaction. Some scientists have reviewed its usage with biogas feedstock to generate synthesis gas because the tri-reforming procedure employs CO2. Furthermore, the tri-reforming procedure is a technique to cut CO2 emissions in flue stack gases. In yielding synthesis gas from biological gas, two chief functioning issues give the anticipated H2/CO ratio that consists of the extreme conversion of methane and also prevents coke deposition. The wanted H2/ CO ratio differs with the wanted usage for the synthesis gas. In the present paper, the published studies from 2001 until now in three classifications have been chosen for further discussion. Finally, various suggestions have been proposed to escape catalyst deactivation due to the high-temperature nature of tri-reforming as a guideline for further investigations.

Thermostabilizing annealing analysis of organomorphic preforms made of oxidized polyacrylonitrile

The simulation results of the thermal stabilization of polyacrylonitrile pressed organomorphic frame samples are presented. The local temperature maximum in the sample depth due to an exothermic oxidation reaction was confirmed. The possibility of the avalanche exothermic effect, which can lead to a sample burnout, is demonstrated theoretically. The analysis of the influence of the initial fiber oxidation degree on the sample temperature state have been carried out.

A pathway to eliminate the gas flow dependency of a hydrocarbon sensor for automotive exhaust applications

Gas sensors will play an essential role in future combustion-based mobility to effectively reduce emissions and monitor the exhausts reliably. In particular, an application in automotive exhausts is challenging due to the high gas temperatures that come along with highly dynamic flow rates. Recently, a thermoelectric hydrocarbon sensor was developed by using materials which are well known in the exhausts and therefore provide the required stability. As a sensing mechanism, the temperature difference that is generated between a catalytically activated area during the exothermic oxidation of said hydrocarbons and an inert area of the sensor is measured by a special screen-printed thermopile structure. As a matter of principle, this thermovoltage significantly depends on the mass flow rate of the exhausts under certain conditions. The present contribution helps to understand this cross effect and proposes a possible setup for its avoidance. By installing the sensor in the correct position of a bypass solution, the gas flow around the sensor is almost free of turbulence. Now, the signal depends only on the hydrocarbon concentration and not on the gas flow. Such a setup may open up new possibilities of applying novel sensors in automotive exhausts for on-board-measurement (OBM) purposes.

Mathematical Model of Iron Reduction with Aluminothermic Method

Utilization of industrial waste in foundry engineering is one of approaches for decrease of production cost price. This technological process may be based on exothermic oxidation-reduction reaction with the resulting formation of iron from dross. Initial charge mixture consists of dispersed aluminum, iron dross and admixtures. This paper is concerned with mathematical modeling of thermite steel production. Presented model takes into account thermal, mechanical and kinetic processes occurring in aluminothermic method of steel melt production.

Research on Production and Pyrophorisity of Iron Sulfur Compounds in Liquid Phase

The production and pyrophorisity of iron sulfur compounds in liquid phase were studied in order to get the spontaneous combustion rules of iron sulfur compounds producted by different ways. In the experiment, FeSO4·7H2O, FeCl2·4H2O, Fe (NO3) 3·9H2O react with (NH4)2Sx and Na2S·9H2O respectively,then the pyrophorisity were analyzed by the exothermic oxidation process of sulfuration productions. The results show that, the pyrophorisity of sulfuration productions formed from (NH4)2Sx and dissolvable iron salt is obviously higher than formed from Na2S and the same dissolvable iron salt. With the increase of dissolvable iron salt concentration, the oxidation pyrophorisity of sulfuration productions formed from (NH4)2Sx also increases. There is some pyrophorisity of sulfuration productions formed from Na2S and dissolvable iron salt. But the pyrophorisity is faint relatively.

Oxidation Dynamics of a Chain of Aluminum Nanoparticles

ABSTRACTMultimillion-atom molecular dynamics simulations are used to investigate burning behavior of a chain of three alumina-coated aluminum nanoparticles (ANPs), where particles one and three are heated above the melting temperature of pure aluminum. The mode and mechanism behind the heat and mass transfer from the hot ANPs (particles one and three) to the middle, cold ANP (particle two) are studied. The hot nanoparticles oxidize first, after which hot Al atoms penetrate into the cold nanoparticle. It is also found that due to the penetration of hot Al atoms, the cold nanoparticle oxidizes at a faster rate than in the initially heated nanoparticles. The calculated speed of penetration is found to be 54 m/s, which is within the range of experimentally measured flame propagation rates. As the atoms penetrate into the central ANP, they maintain their relative positions. The atoms from the shell of the central ANP form the first layer, which is followed by the atoms from the shell of the outer ANP making the second layer and lastly the atoms from the core of the outer ANPs form the third layer. In addition to heating the central ANP by convection, the ejected hot Al atoms from the outer ANPs initiate exothermic oxidation reactions inside the central ANP, leading to further heating within the central ANP. During 1 ns, all three ANPs fuse together, forming a single ellipsoidal aggregate.

Preparation of Ultrafine Cobalt Ferrite Particles by Solution SHS Method

Nanosized CoFe2O4powders of 12nm particle size were directly prepared by solution SHS method at room temperature. The overall process involves three steps: formation of homogeneous sol; formatiom of dried gel; and combustion of the dried gel. Experiments revealed that CoFe2O4dried gel derived from citrate and nitrate sol exhibited self-propagation combustion(SHS) at room temperature once it was ignited in air. After self-propagating combustion, the gel directly transforms into nanosized CoFe2O4particles. The self-propagating combustion was considered as a heat-induced exothermic oxidation-reduction reaction between nitrate ions and carboxyl group. Differential thermal analysis-thermogravimetry (DTA-TG) was used to study the decomposition of the precursor. The structure of the nanosized CoFe2O4powders was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM).