Investigation of the effect of thermal conversion of propane-butane mixture with various metals on the yield of main products

. In the work, the effect of thermal conversion of the propane-butane mixture on the yield of the main products and the effect of transformation with different metals was studied. In the temperature range of 750-800 ℃, compared to the results with the catalyst created for the decomposition process of the propane-butane mixture at high temperatures, a decrease in the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, and an increase in the formation of hydrogen solids were observed. However, the conversion rate increased with increasing temperature, and the catalyst developed for propane-butane cracking at high temperatures was higher in the presence of 5%Ni. The transformation of 5%CoO*5%NiO*2%ZrO 2 *8%Na 2 SO 4 with chromium in the temperature range of 600-750℃ allows to obtain ethylene 5.85 - 13.41%, propylene 3.56-7.14% and the total yield of lower molecular unsaturated hydrocarbons, i.e. ethylene, propylene and butylene 15.42-31.77%. At the same time, the conversion rate has increased. In this case, its values were much higher in the relatively low process temperature range compared to the results of untransformed 5%CoO*5%NiO*2%ZrO 2 *8%Na 2 SO 4 . In addition, the highest yield of propylene at 750 ℃ was 17.47%, the highest yield of propylene in the presence of untransformed 5%CoO*5%NiO*2%ZrO 2 *8%Na 2 SO 4 was 16%, and -15.12% as a result of temperature-induced changes. The purpose of the work is to study the effect of transformation of the catalyst with different metals on the rate of decomposition reaction of propane-butane mixture at high temperatures and yield of main products.


Introduction
Fossil fuels have historically been used as the main sources of energy for human life [1].However, fossil fuels are a finite resource and will run out.Consequently, researching a sustainable and renewable energy source to replace non-renewable fuels has become one of the challenges for our society [1,2].Among all renewable resources, biomass [4][5][6][7][8] and waste plastic [9] have attracted much attention.Compared to natural fuels, biomass has a good reputation for its abundance and carbon neutrality and can be used to produce valueadded bioenergy and biomaterials [3,8].
Bioenergy production can be achieved by converting biomass through thermal and biological processes.Among the thermal processes, high-temperature cracking is the most promising approach widely used in the production of bio-oil, which can be used as a raw material for the production of biofuels and biogasoline, biodiesel or biochemicals [10,11].
However, bio-oils need to be upgraded before they can be widely used as fuel sources.This is because bio-oils extracted at high temperatures from biomass usually contain highly oxygenated compounds that reduce the quality of bio-oil.In addition, the predominance of oxygen content in bio-oil can cause problems such as low calorific value and high corrosiveness during heat treatment [12,13].
Several bio-oil upgrading methods have been developed in recent years.Among these methods, catalytic cracking is the most convenient because it can be applied to hightemperature cracking vapours and liquid bio-oils [14].Catalytic fast high-temperature decomposition is a method based on catalytic decomposition.With the help of a catalyst, the degradation of heavy molecules into lighter molecules is enhanced, as well as the deoxygenation reactions to remove O-types in the form of CO2, CO and/or H2O are improved, thereby improving the properties of bio-oil [15,16].Aromatic hydrocarbons are important starting materials in basic organic synthesis.They are plastics, synthetic fibres, resins, rubbers for various purposes, paints, used for the production of surfactants and pharmaceuticals and agricultural products.The rational use of light hydrocarbons, which are part of natural gas and petroleum processing gases, is an urgent problem.The C1-C4 hydrocarbons in these gases can be converted to aromatic hydrocarbons by zeolite catalysts.Aromatic hydrocarbons are important raw materials for many petrochemical processes.However, until now, most of the light hydrocarbons are used as technological and domestic fuels or burned in flares, which causes significant damage to the environment.Catalysts containing zeolite are widely used in the petrochemical industry today.Research on catalytic conversion of light hydrocarbons is being conducted in many countries of the world.At the same time, the direction of the recycling process and the yield of the product usually depend on the nature, and conditions of preparation of the catalyst and carrying out the process.Catalytic conversion of light hydrocarbons to aromatic hydrocarbons on modified pentacyclic catalysts is intensively studied [17,18].Currently, obtaining unsaturated lower molecular hydrocarbons from natural gas in one step (by oxycondensation of methane), at the same time obtaining them based on the Fischer-Tropsch reaction, converting methane to carbon dioxide and producing diethyl ether and methanol from the resulting product, in time lower molecular unsaturated hydrocarbonsethylene from methanol and diethyl ether, obtaining propylene and butylene is of great interest to world scientists.It should also be noted that finding alternative sources of oil at a time when oil reserves are decreasing is an urgent issue.Today, it is becoming important to create catalysts with high catalytic activity for the catalytic aromatization of petroleum gas and natural gas to obtain unsaturated lower molecular weight alkenes [19][20][21][22][23][24].

Experimental part
Enriched bentonite was used in this work.To determine the pore structure characteristics of bentonite, the adsorption of benzene and water vapour was studied using the BET method before and after acid activation.The Branauer, Emmet and Teller method and equation were used to calculate the relative surface: From this equation m  and SBET constants can be determined Adsorption of benzene and water vapor was measured in a vacuum-adsorption apparatus using Mc-Benn quartz balances.Based on the adsorption-desorption isotherms, the capacity of the monolayer, the percentage of non-desorbed adsorbate, as well as the relative surface area of the adsorbent for water and benzene vapours were determined.The textural characteristics of natural and H-bentonite were found to be equal to the following, respectively: SComp.=72.0 and 170.0 m 2 /g; pore 0,107 V  and 0.1278 cm 3 /g (V = 0.26 for water adsorption); dpore=50 and 80Å; interplanar distance d001-9.8 and 17.6Å.The total pore volume was calculated from the amount of adsorbed nitrogen at maximum saturation.Pore size distribution was determined by the BJH (Barrett-Joyner-Halendr) method.The value of the relative surface area Scomp (m 2 /g) was calculated according to the following formula: The area occupied by one sorbate molecule in the adsorption layer ( )-was found using the following formula, considering the molecules to be spherical: 2/3 4 0,866 42 here, M is the molecular mass,  -sorbate density.
The size distribution of pores was determined using the Thomson (Kelvin) equation: r -the radius of curvature of the surface (the cosine of the wetting angle is assumed to be equal to 1).

Effects of nickel
Tables 1 and 2 show the results of high-temperature conversion of propane-butane mixture in the presence of catalyst 5%CrF3*5%CoO*NiO*ZrO2*Na2SO4 and 5%Ni 5%CoO*5%NiO*2%ZrO2*8%Na2SO4, created for the process of decomposition of propane-butane mixture at high temperatures.According to the experimentally calculated data presented in Table 1, as a result of the addition of 5% of nickel to the catalyst created for the decomposition of the propane-butane mixture at high temperatures, the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, was increased.At the same time, the yield of lower olefins, that is, lower molecular unsaturated hydrocarbons, that is, ethylene, propylene, and butylene, was higher in the operating temperature range up to 750 ℃, but it was lower than the yield of ethylene in the presence of a catalyst created for the process of cracking the untransformed propane-butane mixture at high temperatures.In the temperature range of 750-800 ℃, compared to the results with the catalyst created for the decomposition process of the propane-butane mixture at high temperatures, a decrease in the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, and an increase in the formation of hydrogen solids were observed.However, the conversion rate increased with increasing temperature, and the catalyst developed for propane-butane cracking at high temperatures was higher in the presence of 5%Ni.The data presented in Table 2 is similar to the experimentally calculated data presented in Table 1.The catalyst created for the decomposition of the propane-butane mixture at high temperatures in the presence of 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 produces lower olefins, i.e. lower molecular unsaturated hydrocarbons, i.e. ethylene, propylene and butylene, in the temperature range of 600-700 ℃. shows that the catalyst developed for the decomposition process of the non-acylated propane-butane mixture at high temperatures increased compared to the results with 5%CoO*5%NiO*2%ZrO2*8%Na2SO4.When the temperature was further increased to 800, the yield of lower olefins, i.e., lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, decreased, and the yield of reaction byproducts increased.
Thus, nickel-transformed catalysts lead to higher yields of lower olefins.However, at the same time, the yield of organic matter increases significantly.

Effects of cobalt
Tables 3 and 4 show the results of high-temperature conversion of propane-butane mixture in the presence of catalysts 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 and 5Со-5%CrF3*CoF2*5%NiF2*2%ZrO2*8%Na2SO4, created for the decomposition of propanebutane mixture at high temperatures.The results presented in Table 3 show that metallic cobalt helped to increase the yield of lower olefins, i.e. lower molecular unsaturated hydrocarbons i.e. ethylene, propylene and butylene, in the temperature range of 600-750 ℃.Thus, in this temperature range, the yield of ethylene increased by 2.81-14.61%and the yield of propylene by 3.38-8.1%.At the same time, the total yield of lower molecular unsaturated hydrocarbons, namely ethylene, propylene and butylene, increased by 1.13-23.06%.The conversion rate increased by 4.98 -36.04% over the entire temperature range of the tests.The results of the data presented in Table 4 show that the introduction of metallic cobalt into the composition of 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 did not lead to an increase in the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene at temperatures below 700 ℃, compared to the catalyst created for the process of cracking the untransformed propane-butane mixture at high temperatures.An increase in process temperature increased the yield of lower olefins, i.e. lower molecular unsaturated hydrocarbons, i.e. ethylene, propylene and butylene.At the same time, the highest yield of ethylene and the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, was achieved at a temperature of 800 ℃, and at a temperature of 750 ℃, the highest yield of propylene was achieved.

Effect of chromium
To evaluate the effect of chromium in the catalysts created for the decomposition of the propane-butane mixture at high temperatures, samples with a chromium content of 5% were first prepared.Subsequently, the chromium content was reduced by 2% in the catalyst samples created for the process of cracking the tested propane-butane mixture at high temperatures.
The results of high-temperature conversion of propane-butane mixture with 5%Crcatalyst 5%Cr and catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 for propanebutane mixture decomposition at high temperatures are presented in Tables 5 and 6.According to the experimentally calculated data presented in Table 5, the total yield of lower molecular unsaturated hydrocarbons, i.e. ethylene, propylene and butylene, was created for the decomposition of the propane-butane mixture at high temperatures.was significantly higher in the presence of a catalyst designed for the high-temperature cracking process of the non-acylated propane-butane mixture, especially in the relatively lowtemperature range of the test process.Thus, the transformation of 55%CoO*5%NiO*2%ZrO2*8%Na2SO4 with chromium in the temperature range of 600-750 ℃ yields ethylene 5.85 -13.41%, propylene 3.56-7.14%and lower molecular unsaturated hydrocarbons, i.e. ethylene, the total yield of propylene and butylene allows obtaining 15.42-31.77%more.At the same time, the conversion rate has increased.In this case, its values were much higher in the relatively low process temperature range compared to the results of untransformed 5%CoO*5%NiO*2%ZrO2*8%Na2SO4.In addition, the highest propylene yield was 17.47% at 750℃, the highest propylene yield was 16% in the presence of untransformed 5%CoO*5%NiO*2%ZrO2*8%Na2SO4, and -15.12% as a result of temperature-induced changes.
The data presented in Table 6 show that the reduction of chromium content in 2%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4, a catalyst created for the high-temperature cracking process of propane-butane mixture, contributed to an increase in the yield of ethylene and the yield of lower molecular unsaturated hydrocarbons, namely ethylene, propylene, and butylene, and a decrease in the yield of propylene, compared to the results of a catalyst created for the process of cracking a propane-butane mixture at high temperatures above 750 ℃ with the presence of 2%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4.The results of high-temperature conversion of propane-butane mixture in the presence of catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 and 2%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 are presented in Tables 7 and 8. increased by %.The conversion rate increased with increasing temperature and reached a maximum at 800 ℃.In addition, the decrease in the amount of chromium in the catalyst created for the high-temperature decomposition of the propane-butane mixture led to a decrease in the yield of resin solids.
As can be seen from the data presented in Tables 7 and 8, the inclusion of 5% chromium in the catalyst composition for the decomposition of the propane-butane mixture at high temperatures of 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 increased the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene.However, in this case, the increase in yield of lower olefins, that is, lower molecular unsaturated hydrocarbons, that is, ethylene, propylene, and butylene, occurred in the temperature range of 700÷750 ℃.A decrease in the amount of chromium in the catalyst created for the process of cracking the propane-butane mixture at high temperatures, especially in the temperature range of 650-750 ℃, the catalyst created for the high-temperature decomposition of propane-butane mixture with 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 led to an increase in the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene.At the same time, there was a decrease in the yield of organic matter.
As can be seen from the data presented in Tables 7 and 8, the inclusion of 5% chromium in the catalyst composition for the decomposition of the propane-butane mixture at high temperatures of 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 increased the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene.However, in this case, the production of lower olefins, i.e. lower molecular unsaturated hydrocarbons, i.e. ethylene, propylene and butylene, decreased the amount of chromium in the temperature range of 700÷750 ℃.As can be seen from the data presented in Tables 7 and 8, the addition of 5% chromium in the catalyst composition for the high-temperature decomposition of propane-butane mixture 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 increased the yield of ethylene, propylene, and the total yield of unsaturated hydrocarbons.However, in this case, the increase in yield of lower olefins, that is, lower molecular unsaturated hydrocarbons, that is, ethylene, propylene, and butylene, occurred in the temperature range of 700÷750 ℃.A decrease in the amount of chromium in the catalyst created for the process of cracking the propanebutane mixture at high temperatures, especially in the temperature range of 650-750 ℃, the catalyst created for the decomposition process of the propane-butane mixture at high temperatures in the presence of 5%Cr-5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 led to an increase in the total yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, compared to the results of the conversion of propane-butane mixture.At the same time, there was a decrease in the yield of organic matter.
The results presented in Tables 9 and 10 are compared with the results of tests involving the addition of 5% chromium to the catalyst 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 for the decomposition of the propane-butane mixture at high temperatures with the addition of ethylene, propylene yield and the catalyst 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 for the decomposition of the untransformed propane-butane mixture at high temperatures.shows that the total yield of lower molecular weight unsaturated hydrocarbons, namely ethylene, propylene and butylene, can increase over the entire temperature range.Meanwhile, a propylene yield of 17.89% was achieved at 750 ℃.At the same time, the conversion rate reached 91.37% at 800 ℃.
A decrease in chromium input from 5 to 2% resulted in a slight decrease in the yield of lower molecular weight unsaturated hydrocarbons, namely ethylene, propylene, and butylene.In addition, ethylene reduction occurred in the temperature range of 600-750 ℃.On the contrary, at 800 ℃, in the presence of the catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4, which was created for the process of propanebutane mixture decomposition at high temperatures, the yield of ethylene increased and was higher by 1.16%.At the same time, the yield of organic matter decreased.
The data presented in Tables 11 and 12 are the catalyst created for the process of propane-butane decomposition at high temperatures, the transformation of 5%CrF3*CoF2*5%NiF2*2%ZrO2*8%Na2SO4 with chromium in the amount of 5%, ethylene, propylene yield and untransformed 5%CrF3*CoF2*5%NiF2*2%ZrO2*8%Na2SO4 propane-butane mixture at high temperature compared to the results of the catalyst created for the cracking process in 2010, it led to an increase in the overall yield of lower molecular unsaturated hydrocarbons, i.e., ethylene, propylene, and butylene, in the entire temperature range.At the same time, it should be noted that the yield of organic matter decreases.
Reducing the input chromium content from 5 to 2% resulted in a slight decrease in ethylene yield at temperatures above 700 ℃ and at the same time an increase in ethylene yield compared to the results of the catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 developed for the high-temperature cracking process of propane-butane mixture at 600-650 ℃.The total yield of lower molecular weight unsaturated hydrocarbons, namely ethylene, propylene and butylene, increased at low process temperatures and its growth decreased slightly.
It should also be noted that the yield of resin solids decreases with a decrease in the amount of chromium in an optimal catalyst.Chromium has a high dehydrating capacity and helps to increase the yield of lower olefins, i.e. lower molecular unsaturated hydrocarbons, i.e. ethylene, propylene and butylene.Moreover, the best results were obtained with 5%CoO*5%NiO*2%ZrO2*8%Na2SO4 and 5%CrF3*CoF2*5%NiF2*2%ZrO2*8%Na2SO4 chromium transformation.In addition, a decrease in the yield of solids was noted.

Conclusions
A slight decrease in the yield of tar and tar-like substances was noted in the presence of chromium-preserving catalysts created for the high-temperature decomposition of the propane-butane mixture.The total yield of ethylene, propylene and butylene in the presence of 5%Cr-preserved mesoporous zeolite, a catalyst created for the decomposition process of propane-butane mixture at high temperatures, and the total yield of ethylene, propylene and butylene in the presence of untransformed mesoporous zeolite preservative, the catalyst created for the decomposition process of propane-butane mixture at high temperatures, was significantly higher, especially in the relatively low research temperatures of the process.Therefore, the mesoporous zeolite preservative, the catalyst created for the hightemperature cracking process of propane-butane mixture with chromium in the temperature range of 600-750 ℃, transforms ethylene 5, 85-13.41%,propylene by 3.56-7.14%,and ethylene, propylene and butylene yield by 15.42-31.77%.At the same time, the conversion rate increased over the same temperature range.In addition, it should be noted that the maximum yield of 17.47% of propylene was observed at a temperature of 750 ℃, while the yield of propylene was 16% in the presence of a non-transformed mesoporous zeolite preservative, a catalyst created for the decomposition of a propane-butane mixture at high temperatures, and 15.12% as a result of temperature changes.Mesoporous zeolite preservative, in the composition of the catalyst created for the decomposition of propanebutane mixture at high temperatures (5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4), reducing the amount of chromium to 2% makes it possible to increase the yield of ethylene, propylene and butylene, as well as mesoporous zeolite preservative, A catalyst designed for high-temperature propane-butane cracking resulted in a decrease in propylene yield at temperatures above 750 ℃ compared to the results in the presence of 5%Cr.At the same time, in the temperature range of 600-750 ℃, the yield of ethylene increased by 9.77-22.54%,the yield of propylene by 5.7-7.93%, and the yield of ethylene, propylene and butylene by 3.28-31.19%,compared to the results of the catalyst created for the decomposition of the propane-butane mixture at high temperatures.A decrease in the amount of chromium in the catalyst created for the high-temperature decomposition of the propane-butane mixture led to a decrease in the yields of tar and tar-like substances.Similar results were obtained with mesoporous zeolite-preserved catalysts designed for hightemperature cracking of propane-butane mixtures.

Table 1 .
The effect of nickel in the catalyst content on the yield of the main products for the process of decomposition of the propane-butane mixture at high temperatures

Table 2 .
The effect of nickel in the catalyst 5%Ni-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 4 .
The effect of metallic cobalt in the catalyst 5Со-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 5 .
The effect of chromium in the catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 6 .
The effect of chromium in the catalyst 2%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 7 .
19e effect of chromium in the catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures , in the temperature range of 600-750 ℃, the yield of ethylene is 9.77-22.54%,propylene is 5.7-7.93%, and the total yield of lower molecular unsaturated hydrocarbons, namely ethylene, propylene and butylene is 3.28 -31.19

Table 8 .
The effect of chromium in the catalyst 2%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 9 .
The effect of chromium in the catalyst 5%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 10 .
The effect of chromium in the catalyst 2%Cr-5%CoO*5%NiO*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 11 .
The effect of chromium in the catalyst 5%Сr-5%CrF3*CoF2*5%NiF2*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures

Table 12 .
The effect of chromium in the catalyst 2%Сr-5%CrF3*CoF2*5%NiF2*2%ZrO2*8%Na2SO4 on the yield of the main products created for the decomposition of the propane-butane mixture at high temperatures