Preparation method for fumaric acid pour point depressant for crude oil

Abstract

A fumaric acid pour point depressant for crude oil and a preparation method therefor are provided. The fumaric acid pour point depressant is obtained by polymerizing a first prepolymer, a second prepolymer, a third monomer and a fourth monomer, where the first prepolymer is obtained by pre-polymerizing vinyl acetate and a first monomer; and the second prepolymer is obtained by pre-polymerizing fumaric acid and a second monomer.

Claims

1. A preparation method for a fumaric acid pour point depressant for crude oil, comprising the following steps: pre-polymerizing vinyl acetate and a first monomer having a weight ratio of (1-10):1 to obtain a first prepolymer with a degree of polymerization of 20-40; pre-polymerizing fumaric acid and a second monomer having a weight ratio of (10-50):1 to obtain a second prepolymer with a degree of polymerization of 18-50; and adding a third monomer to the second prepolymer, performing esterification for no more than 1 hour, then adding the first prepolymer and a fourth monomer, and performing polymerization for at least 3 hours to obtain the fumaric acid pour point depressant for crude oil; the first prepolymer, the second prepolymer, the third monomer and the fourth monomer have a weight ratio of (5-25):(10-80):(5-20):(2-25); the first monomer is a mixture of N-vinylpyrrolidone and 2-(N-acryloyloxy)ethylpyrrolidone; and the N-vinylpyrrolidone and the 2-(N-acryloyloxy)ethylpyrrolidone have a weight ratio of (1-6):1; the second monomer is a mixture of allyl polyether and allyl alcohol polyether; and the allyl polyether and the allyl alcohol polyether have a weight ratio of 1:(10-35); the third monomer is a mixture of tetradecanol, hexadecanol, octadecanol and eicosanol; and the tetradecanol, the hexadecanol, the octadecanol and the eicosanol have a weight ratio of (1-10):1:(1-5):(1-5); the fourth monomer is a mixture of acrylamide and N-(hydroxymethyl)acrylamide; and the acrylamide and the N-(hydroxymethyl)acrylamide have a weight ratio of (1-15):1.

2. The preparation method according to claim 1, wherein a vinyl acetate monomer, the first monomer, and an initiator are dissolved into a solvent and stirred evenly to obtain a mixture solution, nitrogen is introduced, and the mixture solution is heated to 60-75° C. for a reaction for 1-5 hours to obtain the first prepolymer; and in terms of parts by weight, the monomers have a total content of 33-70%, the initiator has a content of 0.2-1.0%, and the balance is the solvent.

3. The preparation method according to claim 1, wherein fumaric acid, the second monomer, a mutual solvent and an initiator are dissolved into a solvent and stirred evenly to obtain a mixture solution, nitrogen is introduced, and the mixture solution is heated to 50-70° C. for a reaction for 1-7 hours to obtain the second prepolymer; and in terms of parts by weight, the monomers have a total content of 40-55%, the mutual solvent has a content of 5-20%, the initiator has a content of 0.2-1.0%, and the balance is the solvent.

4. The preparation method according to claim 1, wherein the third monomer and a catalyst are added to the second prepolymer for a reaction for 0.5-1 hour at 80-110° C., then the first prepolymer, the fourth monomer and a chain transfer agent are added, and the reaction is continued to be carried out for 3-8 hours to obtain the fumaric acid pour point depressant for crude oil; and in terms of parts by weight, the catalyst has a content of 0.2-1.0% and the chain transfer agent has a content of 0.01-0.05%.

5. A fumaric acid pour point depressant for crude oil, wherein the fumaric acid pour point depressant is prepared by the preparation method of claim 1.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present application will be described in detail in combination with the examples hereafter, but the present application is not limited to these examples.

(2) Unless otherwise specified, raw materials and auxiliaries in the examples of the present application can be commercially purchased.

(3) An analysis method in the examples of the present application is as follows:

(4) the obtained pour point depressant was dissolved into crude oil for viscosity and condensation point measurement. A crude oil sample has a condensation point of 33° C., a paraffin content of 23%, a colloidal asphaltene content of 10-15%, and a viscosity of 800-1200 mPa.Math.s. Specific operation was as follows: 0.1 wt % of the pour point depressant was added to 99.9 wt % of crude oil at 60° C. to be stirred for 20 min, then the stirred material was cooled to room temperature, and sampling was performed for testing. The condensation point of each crude oil in which the pour point depressant was added was detected in accordance with the standards of GB/T510-1983; the viscosity was obtained by testing the crude oil containing the pour point depressant at 60° C.; and the flash point was tested by reference to the regulations of GB/T 261.

(5) A Fourier transform infrared spectrometer was used for infrared spectroscopic analysis of the pour point depressant; and the obtained pour point depressant was subjected to test analysis by an attenuated total reflection mode at room temperature.

Example 1

(6) (1) 400.0 g of vinyl acetate, 75.0 g of N-vinylpyrrolidone and 25.0 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer;

(7) (2) 480.0 g of fumaric acid, 0.9 g of allyl polyoxyethylene acetate, and 19.1 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(8) (3) 500.0 g of the second prepolymer was weighed and heated to 85° C., then 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed, and a reaction was carried out for 1 h; and afterwards, 100.0 g of the first prepolymer, 90.0 g of acrylamide, 10.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a fumaric acid pour point depressant 1# for crude oil.

Example 2

(9) (1) 300.0 g of vinyl acetate, 15.0 g of N-vinylpyrrolidone and 15.0 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 668.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 60° C., 2.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 5 h to obtain a first prepolymer; and

(10) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant 2#.

Example 3

(11) 350.0 g of vinyl acetate, 300.0 g of N-vinylpyrrolidone and 50.0 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 290.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 75° C., 10.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 1 h to obtain a first prepolymer; and

(12) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant 3#.

Example 4

(13) Step (1) was the Same as that in Example 1;

(14) (2) 363.6 g of fumaric acid, 3.3 g of allyl polyoxyethylene acetate, and 33.1 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 200.0 g of dimethyl sulfoxide and 398.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 50° C., 2.0 g potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 7 h to obtain a second prepolymer; and

(15) step (3) was the same as that in Example 1 to prepare a pour point depressant 4#.

Example 5

(16) step (1) was the same as that in example 1;

(17) (2) 539.2 g of fumaric acid, 0.3 g of allyl polyoxyethylene acetate, and 10.5 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 50.0 g of dimethyl sulfoxide and 390.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 70° C., 10.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 1 h to obtain a second prepolymer; and

(18) step (3) was the same as that in Example 1 to prepare a pour point depressant 5#.

Example 6

(19) step (1) was the same as that in Example 1;

(20) (2) 480.0 g of fumaric acid, 1.0 g of allyl polyoxyethylene acetate, and 19.0 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 60° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 5 h to obtain a second prepolymer; and

(21) step (3) was the same as that in Example 1 to prepare a pour point depressant 6#.

Example 7

(22) Steps (1) and (2) were the same as those in Example 1; and

(23) (3) 100.0 g of the second prepolymer was weighed and heated to 90° C., then 10.0 g of tetradecanol, 10.0 g of hexadecanol, 30.0 g of octadecanol, 50.0 g of eicosanol and 1.0 g of phosphoric acid were added, uniform stirring was performed, and a reaction was carried out for 0.5 h; and afterwards, 50.0 g of the first prepolymer, 125.0 g of acrylamide, 125.0 g of N-(hydroxymethyl)acrylamide and 0.1 g sodium methoxide were added, and the reaction was continued to be carried out under stirring for 8 h to obtain a pour point depressant 7#.

Example 8

(24) Steps (1) and (2) were the same as those in Example 1; and

(25) (3) 100.0 g of the second prepolymer was weighed and heated to 110° C., then 100.0 g of tetradecanol, 10.0 g of hexadecanol, 50.0 g of octadecanol, 40.0 g of eicosanol and 8.0 g of phosphoric acid were added, uniform stirring was performed, and a reaction was carried out for 1 h; and afterwards, 250.0 g of the first prepolymer, 234.4 g of acrylamide, 15.6 g of N-(hydroxymethyl)acrylamide and 0.4 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 3 h to obtain a pour point depressant 8#.

Example 9

(26) Steps (1) and (2) were the same as those in Example 1; and

(27) (3) 800.0 g of the second prepolymer was weighed and heated to 80° C., then 20.0 g of tetradecanol, 10.0 g of hexadecanol, 10.0 g of octadecanol, 10.0 g of eicosanol and 2.8 g of phosphoric acid were added, uniform stirring was performed, and a reaction was carried out for 1 h; and afterwards, 50.0 g of the first prepolymer, 18.0 g of acrylamide, 2.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant 9#.

Comparative Example 1

(28) Comparative Example 1 differs from Example 1 in that the N-vinylpyrrolidone and the 2-(N-acryloyloxy)ethylpyrrolidone in the first monomer of the step (1) have a weight ratio of 9:1. Specific steps were as follows:

(29) (1) 400.0 g of vinyl acetate, 90.0 g of N-vinylpyrrolidone and 10.0 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer; and

(30) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D1#.

Comparative Example 2

(31) Comparative Example 2 differs from Example 1 in that the N-vinylpyrrolidone and the 2-(N-acryloyloxy)ethylpyrrolidone in the first monomer of the step (1) have a weight ratio of 1:2. Specific steps were as follows:

(32) (1) 400.0 g of vinyl acetate, 33.3 g of N-vinylpyrrolidone and 66.7 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer; and

(33) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D2#.

Comparative Example 3

(34) Comparative Example 3 differs from Example 1 in that the vinyl acetate and the first monomer in the step (1) have a weight ratio of 15:1. Specific steps were as follows:

(35) (1) 468.8 g of vinyl acetate, 23.4 g of N-vinyl pyrrolidone and 7.8 g of 2-(N-acryloyloxy)ethyl pyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer; and

(36) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D3#.

Comparative Example 4

(37) Comparative Example 4 differs from Example 1 in that the vinyl acetate and the first monomer in the step (1) have a weight ratio of 0.6:1. Specific steps were as follows:

(38) (1) 187.5 g of vinyl acetate, 234.4 g of N-vinylpyrrolidone and 78.1 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer; and

(39) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D4#.

Comparative Example 5

(40) Comparative Example 5 differs from Example 1 in that the reaction temperature in the step (1) was 50° C. Specific steps were as follows:

(41) (1) 400.0 g of vinyl acetate, 75.0 g of N-vinylpyrrolidone and 25.0 g of 2-(N-acryloyloxy)ethyl pyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 50° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer; and

(42) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D5#.

Comparative Example 6

(43) Comparative Example 6 differs from Example 1 in that the reaction time after uniform stirring in the step (1) was 0.5 h. Specific steps were as follows:

(44) (1) 400.0 g of vinyl acetate, 75.0 g of N-vinyl pyrrolidone and 25.0 g of 2-(N-acryloyloxy)ethyl pyrrolidinone were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 0.5 h to obtain a first prepolymer; and

(45) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D6#.

Comparative Example 7

(46) Comparative Example 7 differs from Example 1 in that the allyl polyether and the allyl alcohol polyether in the step (2) have a weight ratio of 1:9. Specific steps were as follows:

(47) Step (1) was the same as that in Example 1;

(48) (2) 480.0 g of fumaric acid, 2.0 g of allyl polyoxyethylene acetate, and 18.0 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(49) step (3) was the same as that in Example 1 to prepare a pour point depressant D7#.

Comparative Example 8

(50) Comparative Example 8 differs from Example 1 in that the allyl polyether and the allyl alcohol polyether in the step (2) have a weight ratio of 1:39. Specific steps were as follows:

(51) Step (1) was the same as that in Example 1;

(52) (2) 480.0 g of fumaric acid, 0.5 g of allyl polyoxyethylene acetate, and 19.5 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(53) step (3) was the same as that in Example 1 to prepare a pour point depressant D8#.

Comparative Example 9

(54) Comparative Example 9 differs from Example 1 in that the fumaric acid and the second monomer in the step (2) have a weight ratio of 9:1. Specific steps are as follows:

(55) Step (1) was the same as that in Example 1;

(56) (2) 450.0 g of fumaric acid, 2.4 g of allyl polyoxyethylene acetate, and 47.6 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(57) step (3) was the same as that in Example 1 to prepare a pour point depressant D9#.

Comparative Example 10

(58) Comparative Example 10 differs from Example 1 in that the fumaric acid and the second monomer in the step (2) have a weight ratio of 55:1. Specific steps were as follows:

(59) step (1) was the same as that in Example 1;

(60) (2) 491.1 g of fumaric acid, 0.4 g of allyl polyoxyethylene acetate, and 8.5 g of allyl alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(61) step (3) was the same as that in Example 1 to prepare a pour point depressant D10#.

Comparative Example 11

(62) Comparative Example 11 differs from Example 1 in that the reaction temperature in the step (2) was 40° C. Specific steps were as follows:

(63) step (1) was the same as that in Example 1;

(64) (2) 480.0 g of fumaric acid, 0.9 g of ally polyoxyethylene acetate, and 19.1 g of ally alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 40° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(65) step (3) was the same as that in Example 1 to prepare a pour point depressant D11#.

Comparative Example 12

(66) Comparative Example 12 differs from Example 1 in that the reaction time after uniform stirring in the step (2) was 0.5 h. Specific steps were as follows:

(67) step (1) was the same as that in Example 1;

(68) (2) 480.0 g of fumaric acid, 0.9 g of ally polyoxyethylene acetate, and 19.1 g of ally alcohol polyoxyethylene ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 0.5 h to obtain a second prepolymer; and

(69) step (3) was the same as that in Example 1 to prepare a pour point depressant D12#.

Comparative Example 13

(70) Comparative Example 13 differs from Example 1 in that the tetradecanol, hexadecanol, octadecanol and the eicosanol in the third monomer in the step (3) have a weight ratio of 12:1:1:1. Specific steps were as follows:

(71) steps (1) and (2) were the same as those in Example 1; and

(72) (3) 500.0 g of the second prepolymer were weighed and heated to 85° C., then 120.0 g of tetradecanol, 10.0 g of hexadecanol, 10.0 g of octadecanol, 10.0 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 100.0 g of the first prepolymer, 90.0 g of acrylamide, 10.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D13#.

Comparative Example 14

(73) Comparative Example 14 differs from Example 1 in that the acrylamide and the N-(hydroxymethyl)acrylamide in the fourth monomer in the step (3) have a weight ratio of 19:1. Specific steps were as follows:

(74) steps (1) and (2) were the same as those in Example 1; and

(75) (3) 500.0 g of the second prepolymer were weighed and heated to 85° C., then 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 100.0 g of the first prepolymer, 95.0 g of acrylamide, 5.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D14#.

Comparative Example 15

(76) Comparative Example 15 differs from Example 1 in that the first prepolymer, the second prepolymer, the third monomer and the fourth monomer in the step (3) have a weight ratio of 1:50:15:1. Specific steps were as follows:

(77) Steps (1) and (2) were the same as those in Example 1; and

(78) (3) 500.0 g of the second prepolymer were weighed and heated to 85° C., then 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.0 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 10.0 g of the first prepolymer, 9.0 g of acrylamide, 1.0 g of N-(hydroxymethyl)acrylamide and 0.2 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D15#.

Comparative Example 16

(79) Comparative Example 16 differs from Example 1 in that the first prepolymer and the third monomer in the step (3) was subjected to a reaction at 70° C. Specific steps were as follows:

(80) Steps (1) and (2) were the same as those in Example 1; and

(81) (3) 500.0 g of the second prepolymer were weighed and heated to 70° C., then 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 100.0 g of the first prepolymer, 90.0 g of acrylamide, 10.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D16#.

Comparative Example 17

(82) Comparative Example 17 differs from Example 1 in that the reaction was carried out under stirring for 2 h after the first prepolymer and the fourth monomer were added in the step (3). Specific steps were as follows:

(83) steps (1) and (2) were the same as those in Example 1; and

(84) (3) 500.0 g of the second prepolymer were weighed and heated to 85° C., then 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 100.0 g of first prepolymer, 90.0 g of acrylamide, 10.0 g of N-(hydroxymethyl) acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 2 h to obtain a pour point depressant D17#.

Comparative Example 18

(85) Comparative Example 18 differs from Example 1 in that the first monomer in the step (1) was replaced by ethylene. Specific steps were as follows:

(86) 400.0 g of vinyl acetate, and 100.0 g of ethylene were respectively weighed and dissolved into 495.0 g of ethanol, then nitrogen was introduced, the mixture was heated to 65° C., 5.0 g of azodiisobutyronitrile was added, uniform stirring was performed, and a reaction was carried out for 3 h to obtain a first prepolymer; and

(87) steps (2) and (3) were the same as those in Example 1 to prepare a pour point depressant D18#.

Comparative Example 19

(88) Comparative Example 19 differs from Example 1 in that the second monomer in the step (2) was replaced by vinyl isobutyl ether. Specific steps were as follows:

(89) step (1) was the same as that in Example 1;

(90) (2) 480.0 g of fumaric acid, and 20.0 g of vinyl isobutyl ether were respectively weighed and dissolved into 100.0 g of dimethyl sulfoxide and 395.0 g of deionized water, then nitrogen was introduced, the mixture was heated to 55° C., 5.0 g of potassium persulfate was added, uniform stirring was performed, and a reaction was carried out for 4 h to obtain a second prepolymer; and

(91) step (3) was the same as that in Example 1 to prepare a pour point depressant D19#.

Comparative Example 20

(92) Comparative Example 20 differs from Example 1 in that the third monomer in the step (3) was replaced by butanol. Specific steps were as follows:

(93) steps (1) and (2) were the same as those in Example 1; and

(94) (3) 500.0 g of the second prepolymer were weighed and heated to 85° C., then 150.0 g of butanol, and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 100.0 g of the first prepolymer, 90.0 g of acrylamide, 10.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D20#.

Comparative Example 21

(95) Comparative Example 21 differs from Example 1 in that the fourth monomer in the step (3) was replaced by vinyl cyclohexane. Specific steps were as follows:

(96) steps (1) and (2) were the same as those in Example 1; and

(97) (3) 500.0 g of the second prepolymer were weighed and heated to 85° C., then 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 100.0 g of the first prepolymer, 100.0 g of vinyl cyclohexane, and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D21#.

Comparative Example 22

(98) Comparative Example 22 differs from Example 1 in that all the monomers and auxiliaries are polymerized together. Specific steps were as follows:

(99) 40.0 g of vinyl acetate, 7.5 g of N-vinylpyrrolidone, and 2.5 g of 2-(N-acryloyloxy)ethylpyrrolidinone were respectively weighed and dissolved into 49.5 g of ethanol, then 5.0 g of azodiisobutyronitrile was added, and uniform stirring was performed to obtain a first component; 240.0 g of fumaric acid, 0.5 g of allyl polyoxyethylene acetate, and 9.5 g of allyl alcohol polyoxyethylene ether were weighed and dissolved into 50.0 g of dimethyl sulfoxide and 197.5 g of deionized water, then 2.5 g of potassium persulfate was added, and uniform stirring was performed to obtain a second component; and the second component was heated to 85° C., then nitrogen was introduced, the first component, 62.5 g of tetradecanol, 12.5 g of hexadecanol, 37.5 g of octadecanol, 37.5 g of eicosanol and 2.5 g of phosphoric acid were added, uniform stirring was performed and a reaction was carried out for 1 h; and afterwards, 90.0 g of acrylamide, 10.0 g of N-(hydroxymethyl)acrylamide and 0.3 g of sodium methoxide were added, and the reaction was continued to be carried out under stirring for 4 h to obtain a pour point depressant D22#.

(100) 0.1 wt % of the pour point depressant obtained in each example and comparative example was added to 0# crude oil for processing. Test results are shown in Table 1.

(101) TABLE-US-00001 TABLE 1 Decreasing Flash Sample Condensation amplitude point Viscosity No. point (° C.) (° C.) (° C.) (mPa .Math. s) 1# 15 18 30 69 2# 19 14 27 103 3# 18 15 29 81 4# 19 14 25 112 5# 18 15 24 124 6# 17 16 25 115 7# 19 14 23 98 8# 18 15 26 120 9# 19 14 24 117 D1# 21 12 19 262 D2# 23 10 20 284 D3# 22 11 18 345 D4# 24 9 22 371 D5# 22 11 20 310 D6# 20 13 21 302 D7# 25 8 19 390 D8# 21 12 23 375 D9# 22 11 22 296 D10# 24 9 21 386 D11# 21 12 24 273 D12# 24 9 19 364 D13# 25 8 20 359 D14# 23 10 20 370 D15# 26 7 21 410 D16# 22 11 22 386 D17# 24 9 23 361 D18# 25 8 22 427 D19# 28 5 20 458 D20# 29 4 18 439 D21# 27 6 19 450 D22# 27 6 17 473

(102) It can be seen from the condensation point and viscosity test of 0.1 wt % of the pour point depressant obtained according to each example and comparative example in crude oil that on the whole, after being processed by each pour point depressant, crude oil has reduced condensation point and viscosity; pour point depressants 1#-9# will decrease the condensation point of the crude oil, wherein, after being processed by the pour point depressant 1#, the crude oil has the minimum condensation point, being up to 15° C. The above result indicates that the pour point depressant obtained by the present application can effectively prevent the wax crystals in crude oil from forming a three-dimensional network structure. Further, the pour point depressant of the present application can come into play in the crude oil transportation to reduce the condensation point of the crude oil, improve the production efficiency, save the cost and expand the transportation volume of the crude oil.

(103) It can be seen from the test result of the pour point depressant in each comparative example in crude oil that monomers and synthesis conditions for the preparation of the pour point depressant will influence the condensation point reduction effect and rheological properties of the pour point depressant for crude oil; the pour point depressant synthesized in each comparative example has the condensation point reduction effect and rheological properties weaker than the pour point depressants of the examples.

(104) What is described above are merely examples of the present application. The protection scope of the present application is not limited to these detailed examples, but determined by the claims of the present application. A person skilled in the art knows that the present application may have various changes and alterations. Any amendment, equivalent replacement, improvement and the like made within the technical idea and principle of the present application should be included within the protection scope of the present application.