scholarly journals Comparison of hydrocarbons synthesis mathematical models for dimethyl ether catalytic transformation process

2019 ◽  
Vol 1334 ◽  
pp. 012018
Author(s):  
V. Doluda ◽  
E. Sulamn ◽  
R. Brovko ◽  
I. Tarasyuk ◽  
D. Filippov ◽  
...  
2020 ◽  
Vol 6 (11) ◽  
pp. 31-39
Author(s):  
R. Brovko ◽  
L. Mushinskii ◽  
V. Doluda

Zeolite deactivation during the methanol transformation into hydrocarbons is a complex chemical process that includes reversible and irreversible degradation of active sites. The irreversible deactivation of the catalyst is associated with the degradation of active sites during long-term functioning of the zeolite under high-temperature exposure conditions of to water vapor as one of the main reaction products. The carbon deposits formation on the catalyst surface is the main cause of reversible deactivation. The formation of carbon can occur both in the cavities of the zeolites channels, which usually leads to a change in the selectivity of the process for light hydrocarbons, and at the junctions of the channels, which leads to pores blockage and a decrease in the activity of the catalyst. In addition, carbon deposition can occur directly on the active site of the zeolite, which also reduces the activity of the catalyst. The study of the synthesized catalytic systems deactivation rate to process time correlation was carried out in a tubular reactor installation of continuous operation, consisting of a reactor for producing dimethyl ether and a reactor for transformation of dimethyl ether into hydrocarbons. Determination of the kinetic regularities of the deactivation process of zeolite H-ZSM-5 makes it possible to adequately describe the actual course of the catalytic transformation of methanol into hydrocarbons. As a result of solving the differential equations of catalyst deactivation by numerical methods, the values of the preexponential factors and activation energies were obtained. Base on the values of the preexponential factors and activation energies, the methanol into hydrocarbons conditions range optimal for the catalytic transformation was determined, providing the minimum rate of catalyst deactivation, Ptotal = 1 Bar, W (methanol) = 2.3 kg (methanol) / (kg (cat) × h), t = 330–360 °C, which correlates with the results of the literature data on the transformation of methanol into zeolite of the H-ZSM-5 type.


Energy ◽  
2015 ◽  
Vol 90 ◽  
pp. 1922-1930 ◽  
Author(s):  
Zhaoxia Zhang ◽  
Peiyan Bi ◽  
Peiwen Jiang ◽  
Minghui Fan ◽  
Shumei Deng ◽  
...  

2020 ◽  
Vol 6 (5) ◽  
pp. 21-28
Author(s):  
M. Dziuba ◽  
I. Navrotskaya ◽  
R. Brovko ◽  
V. Doluda

The universally depleting reserves of traditional hydrocarbons require the development of a technology for producing synthetic hydrocarbons from renewable sources or human waste. Currently, among the possible methods for producing synthetic hydrocarbons, it is necessary to note the Fischer–Tropsch method and the method of methanol / dimethyl ether catalytic transformation. Moreover, the production of synthetic hydrocarbons from synthesis gas — the Fischer–Tropsch method, is suitable for the production of linear hydrocarbons. The hydrocarbons synthesis using methanol / dimethyl ether is suitable for the production of olefins, branched paraffins, aromatic and polyaromatic hydrocarbons. Depending on the synthesis conditions, it is possible to preferentially obtain a certain type of hydrocarbon, which significantly increases the value of this process. In this article modification of zeolite type H-ZSM-5 with zinc is studied in order to increase the yield of liquid hydrocarbons. Zeolite in acid form was treated with zinс acetate solutions of different concentrations, followed by calcination of the samples. The efficiency of the catalysts was studied in a flow tube reactor set-up, and the surface acidity of the samples was also determined. An increase in the zinc content in zeolite contributed to a decrease in the acidity of the samples and modification of their active centers. However, at high zinc content, a separate oxide phase forms, which contributes to a slight increase in acidity. Modification of zeolite with zinc leads to a decrease in the rate of transformation of dimethyl ether and the rate of liquid hydrocarbons formation. However, a general decrease in acidity and modification of zeolite with zinc contributes to a significant decrease in the amount of heavy aromatic compounds formed, with an increase in the amount of gaseous and liquid hydrocarbons being formed.


Author(s):  
Jenö Beyer ◽  
Lajos Tóth

The structural changes during reversible martensitic transformation of near-equiatomic NiTi alloys can best be studied in TEM at around room temperature. Ternary additions like Mn offer this possibility by suppressing the Ms temperature below RT. Besides the stable intermetallic phases (Ti2Ni, TiNi, TiNi3) several metastable phases with various crystallographic structures (rhombohedral, hexagonal, monoclinic, cubic) have also been reported to precipitate due to suitable annealing procedures.TiNi:Mn samples with 0.9 and 1.3 at% Mn were arc melted in argon atmosphere and homogenized at 948 °C for 72 hours in high vacuum in an infrared furnace. After spark cutting slices of 0.2 mm, TEM specimens were prepared by electrochemical polishing with the twin-jet technique in methanol - perchloric acid electrolyte. The TEM study was carried out in a JEOL 200 CX analytical electron microscope.In this paper a new intermetallic phase is reported which has been observed in both samples by TEM during the martensitic transformation process.


2012 ◽  
Vol 2 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Michaela Heese

Members of the Civil Air Navigation Services Organisation have committed themselves to measure and improve safety culture within their organizations by 2013 ( CANSO, 2010 ). This paper attempts to offer support to air navigation service providers that have already implemented a standardized safety culture survey approach, in the process of transforming their safety culture based on existing survey results. First, an overview of the state of the art with respect to safety culture is presented. Then the application of the CANSO safety culture model from theory into practice is demonstrated based on four selected case studies. Finally, a summary of practical examples for driving safety culture change is provided, and critical success factors supporting the safety culture transformation process are discussed.


2019 ◽  
Author(s):  
Alexander Meduna ◽  
Petr Horacek ◽  
Martin Tomko
Keyword(s):  

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