SYNTHESIS OF DEPRESSOR ADDITIVES BASED ON POLYPROPYLENE POWDER AND EFFECT ON LOW-TEMPERATURE PROPERTIES OF DIESEL FUEL

ABSTRACT

The article studies the influence of additives synthesized on the basis of polypropylene copolymers with methyl acrylate on the low-temperature properties of diesel fuel. The results of the study showed that both synthesized depressant additives had a strong inhibitory effect on diesel fuel, while the threshold filtration temperature of 0,4 % diesel fuel was reduced from -10 ⁰С to -22 ⁰С, and the pour point - from -10 ⁰С up to -27 ⁰С.

АННОТАЦИЯ

В статье изучено влияния присадок синтезированных на основе сополимеров полипропилена с метил акрилатом на низкотемпературные свойства дизельного топлива. Результаты исследования показали, что синтезированные депрессорные присадки 0,4% концентрации дизельного топлива предельная температура фильтруемости была снижена с -10 ⁰С до -22 ⁰С, а температура застывания - с -10 ⁰С до -27 ⁰С.

Keywords: polypropylene, powder, copolymer, depressant, additive, isotactic, atactic.

Ключевые слова: полипропилен, порошок, сополимер, депрессор, присадка, изотактик, атактик.

Introduction. The composition of diesel fuel, unlike other types of fuel, can vary significantly depending on the raw materials and production technology. To obtain highly efficient fuels, first of all, it is necessary to select high-quality raw materials and improve the technology of their production. However, it is impossible to solve the problem in principle without the use of additives [1].

The main active components of the developed depressant additives are polymers, vinyl acetate copolymers [2, 3], polymethylacrylate, ethylene poly-α-olefin [4], methacrylate-comalein anhydride [5], vinyl acetate copolymers tetrapolymer consisting of methacrylates with maleic anhydride and methacrylmorpholine and their amine compounds [6], dialkyl fumarate-styrene-vinyl acetate is a terpolymer [7], n-alkylacrylate-vinyl acetate-styrene is a triple copolymer [8], dimethyl fumarate is a vinyl acetate copolymer [9], dimeric surfactants [10].

In addition, the block copolymers polyethylene-poly (ethylene propylene) (PE-PEP), ethylene-propylene show high efficiency as initiators controlling the size of paraffin particles formed in diesel fuel due to the presence of external groups [11, 12].

Our country has a sufficient base of local raw materials (monomers) for the production of synthetic depressors by increasing the production of polymer substances and increasing the production processes of secondary products and waste in addition to the main products [13].

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. Polypropylene powder is obtained by polymerization of propylene using a Ziegler-Natta catalyst (TiCl₄:MgCl₂) nCH₂=CH(CH₃) → [-CH₂-CH(CH₃)-]n when tested on an EVLAS-2M analyzer, the humidity was 10,97 % at a temperature of 102 ⁰C, at 105,5 ⁰C for one minute, a complete humidity drying [14].

Subsequently, the dried polypropylene powder was separated from the high-molecular fractions by re-precipitation from ethyl alcohol in solutions of hexane, heptane and ether, and then purified from the catalyst residues. Isotactic and atactic polypropylene were dissolved in p-xylene at 130-140 ⁰C, when the solution was cooled to 25 ⁰C, the isotactic part was precipitated, and the atactic part was dissolved in p-xylene.

The separated atactic and precipitated isotactic part was dissolved in p-xylene and toluene in the range of 80-90 ⁰C, then a methyl acrylate monomer was added, heated to 75-90 ⁰C and a copolymerization reaction was carried out. The solution was placed in a three-necked flask equipped with a stirrer and a return refrigerator, in a three-necked flask equipped with a stirrer and a thermometer, the amount of polypropylene and methyl acrylate was taken up to 1:9 in organic solvents - toluene, benzene or p-xylene. The resulting copolymer was precipitated with alcohol, the reaction mixture was filtered and weighed after cooling to room temperature.. The number of monomers in the resulting copolymer and the molecular weight of the copolymers, as well as their structure, were checked by IR spectroscopy.

Results and discussion. The structure of the obtained copolymer was analyzed by IR Shimadzu IRAffinity-1S spectroscopy device. Comparing the IR spectra of polypropylene and methyl acrylate copolymers with a polypropylene monomer, one can clearly see the absorption region characteristic of fragments in the IR spectrum of the copolymer.

Figure 1. IRAffinity-1 S FOURIER TRANSFORM INFRARED SPECTRO-PHOTOMETER (SHIMADZU) IR spectrum of grafted polypropylene and methyl acrylate copolymer

It can be seen from the IR spectrum (Fig. 1) that the absorption region of 2866,22 cm^-1 corresponds to g_sim vibrations of the C-H bond in the CH₃ group, the absorption region of 2918,30 cm^-1 corresponds to g_asim valence vibrations of this group, as well as 1375,25 cm^-1 absorption area to d_asim deformation vibration of the C-H bond, 2918,30 cm^-1 absorption area to the valence vibrations of the methylene group CH₂ of the C-H bond, 2839, 22 cm^-1 of the absorption area with the same valence of the methylene group C-H, the vibrations of the C-H bond, the absorption area 2357,01 cm^-1 refers to the vibrations of the alkyl group C-O, The absorption area of 1734,01 cm^-1 refers to the oscillation of the C= O-group bond, and 1166,93 cm^-1 refers to the deformation vibrations of the C-C bond [15].

According to the results, the number of monomers in the ratio 1:1, 4:1, (0,2-0,4 mas. %) in copolymers of polypropylene and methyl acrylates tested in the conditions of the industrial laboratory of the Fergana Oil  Refinery, due to the low-temperature properties of diesel fuel, 0,2 wt.% of copolymers of polypropylene and methyl acrylate in a ratio of 4:1 reduces the turbidity temperature of diesel fuel to -5 ⁰C, the freezing temperature is -26 ⁰C, the maximum filtration temperature is -16 ⁰C, 0,4 wt. % of polypropylene and methyl acrylate copolymers in a ratio of 1:1 Compared with a ratio of 4:1, the lower turbidity temperature did not change at -5 ⁰C, the freezing temperature -27 ⁰C, the maximum filtration temperature -22 ⁰C.

Table 1.

Analysis results

The effect of additives based on polypropylene powder and methyl acrylate on the physic-chemical and operational properties of fuel according to O'ZDTS 989:2001 when introducing a 0,4 % additive solution into hydro treated diesel fuel TD-L of the Fergana Oil Refinery, the general characteristics of the theoretical justification of the effect of additives on improving the low-temperature properties of winter diesel fuel are presented in table -1.

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 0.4 % in the fuel.

Conclusion. As a result of the conducted research, the following conclusion can be made: polypropylene powder from secondary products of the Uz-Kor Gas Chemical LLC polymer workshop can be used as depressant additives to diesel fuel, and when added to summer diesel fuel from a 0.4% additive solution, it improved its low-temperature properties, did not affect the basic physico-chemical properties and was recognized as fully compliant with the technical requirements of O'ZDTS 989:2001

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