METHODOLOGY OF CATALYST RECOVERY USED FOR DECOMPOSITION OF MONOCHLOROMETHANE

ABSTRACT

Research was conducted on the methodology and technology of recovery of the catalyst used for the decomposition of monochloromethane . In this Mg-P-Zr-Fe/YukS-20-microsphere (Mg-P-Zr-Fe/YukS (2.0%Mg₂P₂O₇ +1.0% ZrO₂ +1.0% Fe₂O₃/YukS) catalyst was selected. The failure of the Mg-P-Zr-Fe/YukS-microsphere catalyst is observed due to carbon deposits, and the removal of carbon deposits in the catalyst recovery mode, cleaning and performed in recovery methods . Recovery volume speed 250-100 hours^-1 , 450-550 ⁰ C at temperatures and 30-120 min experiment duration was carried out. At a volumetric rate of 650 h^-1 , the regeneration of the catalyst is 75 minutes, at a volume rate of 250 h^-1 , the regeneration can be increased to 165 minutes, since the activity period is 120 minutes at a volumetric rate of 350 h^-1 , and the duration of regeneration is 120-135 minutes Mg-P- It was confirmed that the activity of the Zr-Fe/YuKS-microspherical catalyst was completely restored. Mg-P-Zr-Fe/YukS-20 microsphere The fact that the conversion of monochloromethane after catalyst regeneration is 70-80% selective for ethylene and propylene is 70-80%, indicating that the regeneration is effective. The purpose of the work is the methodology and technology of regeneration of the catalyst used for decomposition of monochloromethane.

АННОТАЦИЯ

Проведены исследования по методологии и технологии восстановления катализатора, используемого при разложении монохлорметана. В качестве катализатора был выбран Mg-P-Zr-Fe/ЮкС-20-микросфера (Mg-P-Zr-Fe/ЮкС (2,0%Mg2P2O7 +1,0% ZrO2 +1,0% Fe2O3/ЮкС). Неисправность Mg- P-Zr-Fe/ЮкС-микросферный катализатор наблюдается за счет нагара, а удаление нагара в режиме восстановления катализатора, очистка и восстановление объемной скорости 250-100 ч-1, 450-550 0 . С при температурах 30-120 мин. Продолжительность эксперимента. При объемной скорости 650 ч-1 регенерация катализатора составляет 75 мин, при объемной скорости 250 ч-1 регенерация может быть увеличена до 165. минут, так как период активности 120 минут при объемной скорости 350 ч-1, а продолжительность регенерации 120-135 минут Mg-P- Подтверждено, что активность Zr-Fe/ЮКС-микросферического катализатора была микросфера Mg-P-Zr-Fe/ЮкС-20 полностью восстановлена. Тот факт, что конверсия монохлорметана после регенерации катализатора составляет 70-80%, селективность по этилену и пропилену составляет 70-80%, что свидетельствует об эффективности регенерации. Цель работы – методика и технология регенерации катализатора разложения монохлорметана.

Keywords: catalyst , carbon , monochloromethane , ethylene , propylene , reactor , catalyst , selectivity.

Ключевые слова: катализатор, углерод, монохлорметан, этилен, пропилен, реактор, катализатор, селективность.

INTRODUCTION

It is known from previous works that intermediate compounds are converted into condensation products and their further transformation into carbon storage layers, a set of chemical reactions leads to the generation of hydrogen in the decomposition products of monochloromethane [1]. The bputto-reaction of hydrogen formation during the catalytic decomposition of monochloromethane can be imagined as follows [2-4]:

CH₃Cl → C + H₂ + HCl.

The hydrogen formed during the decomposition reaction at a high temperature in the absence of air interacts with monochloromethane to produce methane [ 5-8]:

CH₃Cl + H₂ → CH₄ + HCl.

As noted [ 9,11], the selectivity of C ₂₊ hydrocarbons formation is observed to a certain extent with the increase in volumetric speed under the conditions of increased selectivity of ethylene formation and decreased conversion of monochloromethane . According to the data of previous physicochemical studies of carbonized silicoaluminophosphate YuKS-30 [12-14], its deactivation during heating of monochloromethane is observed with a decrease in the size of its micropores. YuKS-30 and YuKS-30 silicoaluminophosphates were found to be analogs[15]. In the process of heating monochloromethane, the deactivation of YuKS-30 is also observed with a decrease in the size of its micropores[16]. In this case, the sharp decrease of YuKS-30 activity observed when the volumetric rate of monochloromethane is increased in the range of 1000-1500 h^-1 is caused by the process of formation of carbon storage layers and their accumulation [17,18], which leads to the narrowing of silicoaluminummagnesium phosphate cellular channels. and small molecules such as ethylene and propylene are formed in them[19,20].

EXPERIMENTAL PART

A reactor with a selected catalyst layer is used for stationary heating of monochloromethane and production of ethylene and propylene in conducting tests on the selection of an active component based on YKS. The cross-sectional surface of the reactor designed for heating monochloromethane and obtaining hydrocarbons is 3.3 cm² . The volume of loaded catalyst is 3-5 cm³. The remaining volume is filled with a porcelain nozzle.

The air cleaning of the reactor designed to obtain ethylene and propylene by heating monochloromethane is carried out in order to remove the residual amount of unreacted monochloromethane from the reaction zone, as well as the recovery process is carried out in order to release the reactor designed to obtain ethylene and propylene by heating monochloromethane to a temperature regime of -550℃ . Nitrogen is used as a driving gas. Nitrogen is sent from a cylinder to a reactor designed to obtain ethylene and propylene by heating monochloromethane at high temperature in a vacuum. Nitrogen consumption is provided by 5 RRG-10 regulators, which are carried out through the control unit.

EXPERIMENTAL RESULTS AND THEIR DISCUSSION

According to the results of laboratory studies, it is recommended to carry out the process of obtaining propylene and ethylene by heating the spent monochloromethane by burning the oxidizing agent.

Mg-P-Zr-Fe/YukS-20 _- microsphere testing of the regeneration process in a pilot plant was carried out in the temperature range of 450-550 ⁰ C. Air was used as an oxidizer, its volume was 350 h^-1 . Mg-P-Zr-Fe/YukS microsphere The catalyst regeneration selected for the decomposition of monochloromethane was carbonized for 120 min. The catalyst selected for decomposition of monochloromethane has an active regeneration period of 120 minutes, the total selectivity for conversion of monochloromethane and hydrocarbons of the lower unsaturated ethylene series, i.e. ethylene and propylene, is C₂₌ -C₃₌ 70-80 mol% and 80 mol%, respectively.

Picture 1. Mg-P-Zr-Fe/YukS the dependence of the catalyst selected for the decomposition of monochloromethane on the duration of the regeneration process. Volumetric speed -350 h^-1

Recovery at different temperatures The selected catalyst recovery samples for the decomposition of monochloromethane were tested in the process of obtaining propylene and ethylene by heating monochloromethane at high temperature and in a vacuum , the results of which completely confirm all the recoveries.

Research 550 ⁰ C was carried out in the range of 250-650 hours^-1 air supply at a temperature. Previously, 430 ⁰ C of monochloromethane temperature and 1000 h ^-1 volumetric flow rate of monochloromethane for 120 minutes at high temperature and in the absence of air heating during the production of propylene and ethylene was completed.

430 ⁰ C and a volumetric rate of monochloromethane of 1000 h^-1 , the first 2 hours of the selected catalyst recovery for the decomposition of monochloromethane were found to be the optimal regime. The total selectivity of the formation of lower unsaturated ethylene hydrocarbons, i.e., ethylene and propylene, is approximately 82 mol%, and the conversion of monochloromethane is 72 mol..%. The duration of experiments to study the dynamics of formation of carbon deposits is 30 minutes, 60 minutes, 90 minutes. and 120 min.

The general selectivity of formation of lower molecular unsaturated ethylene hydrocarbons, i.e., ethylene and propylene, reaches 81-85 mol% after 500 minutes of operation of silicoaluminummagnesium phosphates: YuKS-300^Si , YuKS-30^Fe , YuKS-30. In the YuKS-30 sample modified with Mg, the value of this indicator is 70 mol% .

Table

Selectivity of formation of pyrolysis products of methyl chloride

Temperature 425 ⁰ C. Volume speed 1200 hours ^{- 1} .

Based on the obtained data, it is typical that the modification of silicoaluminummagnesium phosphates based on YuKS-30 leads to a decrease in monochloromethane conversion, which affects the overall selectivity of the formation of C₂ -C₃ unsaturated ethylene series hydrocarbons, that is, propylene with ethylene. it doesn't matter.

The silicoaluminomagnesium phosphates used in these experiments differ greatly in the type of crystal lattice structure, as well as in the size of the crystals.

Figure 2 shows Mg-P- Zr -Fe/ YUKS -30 composition catalyst of the sample derivativeogram shown.

Figure 2. Mg-P- Zr -Fe/ YKS -30 catalyst of the sample derivativeogram

Adsorption and texture characteristics heterogeneous of catalysts important features is considered Low temperature nitrogenous adsorption-desorption isotherm g hysteresis ring to e to be , own to the shape according to IY U PAK classification according to type IV isotherm as classified . G hysteresis ring type H3 belongs to is , har different in size layered of particles of the structure formation is typical.

Figure 3. Mg-P- Zr -Fe/ YKS -30 catalyst low temperature of the sample nitrogen adsorption-desorption isotherm (a) and BJH pore dimensions distribution (b)

With scanner e lektron from microscopy received to information according to selected catalyst surface one flat They are not located between 10 µm in length and width 1-2 µm up to has been bigger branch shaped particles located​

Figure 4. YUKS-30 based on catalysts example SEM image of the surface (×1000)

According to Fig. 4, the SYeM image of a sample of synthesized aluminosilicate (high-silica zeolite) YuKS-30 based catalysts shows many uniform spherical particles with an average diameter of 610 nm. This diameter is typical for mesoporous aluminosilicates (high-silica zeolite) synthesized in the basic medium, which also indicates the mesoporosity of the obtained samples.

CONCLUSION

Thus, low-temperature nitrogen adsorption/desorption, BET, SYeM, and small-angle X-ray phase analysis data showed that the synthesized samples were characterized by mesoporosity with a hexagonal pore arrangement. Also, mesoporous aluminosilicates (high silica zeolites) retain their structure after annealing at 600ºC to remove the template. But in the case of YuKS-20, for the synthesis of which its isopropoxide was used as a source of aluminum, despite the high specific surface area, there is a decrease in the pore size and mesostructure.

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