DEPRESSOR PROPERTIES OF THE PRODUCTS OF POLYMERANALOGICAL CHANGES OF LOW MOLECULAR POLYPROPYLENE

АННОТАЦИЯ

В сообщении приведены сведения о синтезе депрессорных присадок, применяемых на дизельных топливах и оказывающее ингибирующее действие на них. Присадки синтезированы из полипропиленового порошка при интервале температур 85-90⁰C.

Также обсуждается литература по окислению полиолефинов и приводятся способы получения присадок. По результатам исследования синтезированные присадки оказали сильное ингибирующее действие на дизельное топливо, при этом предельная температура фильтруемости 0.2% дизельного топлива была снижена от -7 ⁰C до -16 ⁰C, а температура застывания от -13 ⁰C до -26 ⁰C.

ABSTRACT

The report provides information on the synthesis of depressant additives used on diesel fuels and has an inhibitory effect on them. Additives are synthesized from polypropylene powder at a temperature range of 85-90⁰C.

The literature on the oxidation of polyolefins is also discussed and methods for producing additives are given. According to the results of the study, the synthesized additives achieve a strong inhibitory effect on diesel fuel, while the threshold filtration temperature of  0.2% diesel fuel was reduced from -7 ⁰C to -16 ⁰C, the pour point  from -13 ⁰C to -26 ⁰C.

Ключевые слова: полипропилен, порошок, депрессор, присадка, полимераналогичные превращение, олигомер, полимер.

Keywords: polypropylene, powder, depressant, additive, polymer analogous transformation, oligomer, polymer.

Introduction. After the independence of the Republic of Uzbekistan, extensive measures were taken to develop technologies for the use of diesel fuel additives and their production. Today, on a global scale, the following works are being carried out on the development of technologies for obtaining installations for diesel fuels: creation of universal devices with a high useful efficiency and obtained on the basis of nanotechnologies for diesel fuels; obtaining depressor-dispersing compounds that improve solidification properties of diesel fuels from secondary raw materials; scientific research is being carried out in current areas such as their use in diesel fuels.

Depressor-dispersing powders are compositions consisting of components with different functional groups. Depressor additives do not lower the filtration limit temperature and solidification temperature of diesel fuel, and dispersing additives prevent the crystallization of n-paraffin’s in diesel fuel at lower temperatures. With the rapid development of techniques and technologies in our republic, issues of environmental protection are one of the most urgent problems in the oil and oil refining industry.

The production of the first polypropylene granules in our republic was carried out with the launch of the "Uz-Kor Gas Chemical" LLC enterprise. This, in turn, meets the domestic market's demand for polypropylene and contributes to the export potential. The product production process at "Uz-Kor Gas Chemical" JV LLC started as a test in 2015. In 2015, more than 54,900 tons of liquefied hydrocarbon gas, more than 34,000 tons of gas condensate were produced, and more than 186,000 tons of polyethylene and polypropylene were shipped to the countries of Central and East Asia, CIS and Europe.

In recent years, in our Republic, several scientists have studied the synthesis of materials using internal raw material bases, which are considered as waste products of existing production processes [1].

Objects and methods of research. The raw material we selected is a secondary product of the polymer production process at Uz-Kor Gas Chemical LLC.

At the beginning of the study, when we weighed the raw materials on the scale and checked them in the EVLAS-2M moisture analyzer, the moisture content was 10.97% at a temperature of 102⁰C, complete drying was carried out at 105.5 ⁰C for one minute. The low molecular weight atactic polypropylene-ethyl alcohol was then separated from the high molecular weight portion by reprecipitation from hexane, heptane, and ether solutions, followed by purification of catalyst residues. A catalyst based on manganese (IV) oxide soaked in aluminum oxide [2] was prepared according to a known method. Oxidation of atactic polypropylene oligomer was carried out under the following conditions: in the presence of a catalyst in the amount of 0.5 %, the air speed for 1 g of raw material is 0.5 l/h. Oxidation is carried out in a heptane, nonane solution at a temperature of 140⁰C for 6 hours.

Etherification of the oxidation product of atactic polypropylene oligomer is carried out in the medium of propyl and butyl alcohols, in the presence of a catalyst, at a temperature of 90⁰C for 6 hours in a four-mouth round-bottomed flask equipped with a Din-Stark apparatus, until the release of water stops.

The structure of the synthesized compound was determined using an IRAffinity-1S (SHIMADZU) spectrometer.

Results and discussion. The authors [3] analyzed the mechanisms of action related to the molecular structure of depressor compounds and the research results showing depressor effects in polymer chemistry.

The additives that improve the low-temperature properties of diesel fuel, which we are conducting theoretical research on, are used in diesel fuel, which contains paraffin hydrocarbons in a dissolved state, and when the temperature drops below -5⁰C, the paraffin hydrocarbons in the fuel without depressor additives crystallize and form precipitates.

Crystals block the fuel filter because their size is much larger than the filter holes. It is also possible to see cases where paraffin hydrocarbons stick to the internal walls of fuel engines and other parts of the fuel equipment, which in turn causes the fuel to not flow normally into the engine, we can prevent these phenomena by adding depressants [4].

Tests of additives for diesel fuels [5] in the amount of 0.05-1.0% showed that it did not affect the solidification temperature of diesel fuel at 24⁰C, the filtration limit temperature of 8⁰C, and the clouding temperature of diesel fuel in summer, and the corresponding solidification temperature at 19⁰C and the filtration limit temperature of 19⁰C in winter and lowering the turbidity temperature to 10⁰C was determined based on experiments.

As a result of complex studies on the effect of nitrogen-, sulfur-, and oxygen heterocyclic compounds on the low-temperature properties of fuels, it was determined that an increase in the amount of sulfur in diesel fuel from 0.4 to 1.0% has almost no effect on the effectiveness of depressant additives [6]. 

We tested the depressor properties of the synthesized compound in laboratory conditions on diesel fuel obtained from unit 13 of the Bukhara Oil Refinery. The test results are presented in the table below.

Table 1.

Test results of depressor properties of synthesized oxidized polypropylene etherification product

- 4  ± 0.01

From the obtained results, it can be seen that the developed depressor has a positive effect on the solidification temperature of diesel fuel when it is used in the amount of 0.1-0.4 % in the fuel.

This can be explained by the fact that it is a low molecular polypropylene containing complex ether groups, its branched structure with a high molecular weight acts as a copolymer of polypropylene and methyl acrylate, which is easily soluble in diesel fuel.

In the IK spectra of etherification products of moderate intensity, the absorption region of 1734 cm^-1 belongs to С=O-groups of aliphatic ethers, in the absorption region of 2918 cm^-1 it is related to the methylene group –CH₂–O–C and the band with an absorption area of 2866 cm^-1 is due to the symmetric vibration of the aliphatic -CH₃ group. These results are confirmed by literature data [7-8].

Thus, the substances obtained by etherification of the oxidation products of polypropylene, according to IК spectroscopic studies, it is estimated that complex ether functional groups are formed in the molecules of this high molecular weight compound, so it can be considered copolymers of propylene with methyl acrylate.

Thus, as a result of polymer logical changes of polypropylene oligomers based on the oxidation reaction, etherification of polypropylene and oxidation products with lower alcohols, we obtained a depressor compound containing an ether functional group with the depressant property of reducing the solidification temperature of diesel fuel produced at the Bukhara oil refinery.

Conclusion. Data analysis [9] showed that polymeric materials are effective additives to achieve the above requirements. It is known that many depressor compounds that reduce the solidification temperature of diesel fuel contain complex ether groups.

Therefore, the compound we synthesized may exhibit the same depressor-dispersing properties.

As a result of the conducted research, the following can be concluded: It was found that polypropylene powder, secondary waste of the Us yurtgaz chemical complex, can be used as a depressor-dispersant for fuels obtained from petroleum products.

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