CN102220171A - Corrosion inhibitor and preparation method thereof - Google Patents

Abstract

The invention provides a corrosion inhibitor and a preparation method thereof. The corrosion inhibitor is a thiophosphates corrosion inhibitor which is a mixture of two substances with a general structure A and a general structure B respectively, wherein a ratio of A to B is changed with reaction conditions. The corrosion inhibitor contains a plurality of heteroatoms of P, S, N and O, and polar groups centering around the heteroatoms enhance bonding force and bonding strength between the corrosion inhibitor and a metal surface. An annular structure with branches increases coverage and film thickness of the corrosion inhibitor on the metal surface, and substantially increases inhibition efficiency of the corrosion inhibitor. In addition, the preparation method of the corrosion inhibitor is simple, and the corrosion inhibitor is characterized by low toxicity and high efficiency. The general structure A and the general structure B are shown as below.

Description

A kind of inhibiter and preparation method thereof

Technical field

The invention belongs to the refining of petroleum field, more particularly relate to a kind of high-temperature corrosion inhibitor that is applicable to oil refining apparatus metallic substance high temperature position naphthenic acid and sulfide corrosion and preparation method thereof.

Background technology

In recent years, along with the Oil extraction degree of depth increases, the aggravation of crude oil poor qualityization trend, the output of high-sulfur high-acid crude oil increases fast, causes the naphthenic acid corrosion and the sulfur corrosion aggravation of oil refining apparatus high temperature position, has brought very big potential safety hazard to oil refining enterprise.The method of slowing down naphthenic acid corrosion has a lot, as height acid number crude oil mixing, remove naphthenic acid, upgrade of material and interpolation inhibiter etc. from crude oil.Wherein the first three methods existence is limited by reasons such as raw material restriction, deacidifying process complexity, upgrade of material cost height, has certain limitation.Adding inhibiter, to suppress naphthenic acid corrosion be a kind of effective, method that cost is low, simple to operate, obtained widespread use.

High-temperature corrosion inhibitor can be divided into phosphorus system, sulphur system and mixed type usually.Patent USP5611911, USP5500107, USP5314643 are alkyl, aryl groups per alkyl group phosphoric acid ester inhibiter, exist consumption big, the shortcoming that inhibition efficiency is low; Patent USP5630964 is the simple composite inhibiter that forms of phosphoric acid ester and organic polysulfide, and consumption is big, and it is poor to suppress corrosive effect; Patent USP5863415, USP5552085, CN200610018059.9 are the thiophosphatephosphorothioate inhibiter, have the unfavorable shortcoming of corrosion mitigating effect; Patent CN92109528.7 and USP5252254 are respectively piperazines and sulfonation nonylphenol class inhibiter, preparation method's complexity, and corrosion mitigating effect is poor.Therefore exploitation has that preparation technology is simple, consumption is little, corrosion inhibition rate is high and is from now on development trend to the inhibiter of characteristics such as following process toxicity is little.

Summary of the invention

The object of the present invention is to provide that a kind of preparation technology is simple, consumption is little and the efficient naphthenic acid inhibiter little to following process toxicity.

Inhibiter provided by the invention is a kind of film inhibitor, is the mixture with two kinds of materials of general structure A and general structure B, and wherein the ratio of A and B changes with change in reaction conditions.General structure A and B are as follows:

R wherein ₁And R ₂Be the alkyl of C6～C18, the alkyl of preferred C8～C10, R ₁With R ₂Carbon chain lengths can be the same or different R generally ₁With R ₂Identical; X is oxygen or sulphur, is sulphur but have an X in each general formula at least, and m is 1～4 integer.

Inhibiter preparation method of the present invention is as follows:

(1) preparation of thiophosphatephosphorothioate

Fatty Alcohol(C12-C14 and C12-C18) and organic solvent are placed reactor, heat to 120 ℃, add thiophosphoric anhydride in batches, be warming up to 160～190 ℃ then, reacted 3～7 hours, the generating structure general formula is the thiophosphatephosphorothioate compounds of C and D.

Wherein R, R ₁And R ₂Alkyl for C6～C18; R, R ₁With R ₂Carbon chain lengths can be the same or different generally R, R ₁With R ₂Identical; X is oxygen or sulphur, is sulphur but have an X in each general formula at least.

Described Fatty Alcohol(C12-C14 and C12-C18) is straight or branched Fatty Alcohol(C12-C14 and C12-C18) or its mixture of C6～C18, preferred C8～C10 Fatty Alcohol(C12-C14 and C12-C18).

(2) preparation of imidazolidine thione compounds

Equimolar thiocarbamide and polyethylene polyamine are placed a reactor with condensing works, stir and the feeding nitrogen protection, reacted about 150～180 ℃ 4～6 hours, the generating structure formula is the imidazolidine thione compounds of E.

Wherein n is 2～5 integer, described polyethylene polyamine be in diethylenetriamine, triethylene tetramine, tetraethylene pentamine, the five ethene hexamines any one, preferred diethylenetriamine.

(3) preparation of inhibiter

The imidazolidine thione compounds that phosphorothioate compound that above-mentioned steps (1) is obtained and step (2) obtain can obtain inhibiter of the present invention reaction under 60～80 ℃ of conditions about 1 hour.

Inhibiter provided by the invention can be used on the oil refining apparatus greater than 220 ℃, with hardware and pipeline that acid-containing raw oil or distillate contact in; under the condition of add-on 10～100ppm; heteroatomss such as the P that contains in the inhibiter, S and N; lone-pair electron can be provided; thereby combine the formation firm protective with atoms metal Fe coordination; the contact channels of blocking-up naphthenic acid and metal is avoided the corrosive effect thereby play the protection metal.

High-temperature corrosion inhibitor provided by the invention contains a plurality of P, S, N and O heteroatoms simultaneously, is the polar group at center with these heteroatomss, has strengthened the bonding force and the bonding strength of inhibiter and metallic surface; Have band ramose ring texture, improve coverage and the film forming thickness of inhibiter, improve the corrosion inhibition rate of inhibiter greatly in the metallic surface.The raw material of this inhibiter is cheap and easy to get simultaneously, and the preparation method is simple, and is little to the murder by poisoning of secondary processing device, is a kind of low toxicity inhibiter efficiently.

Embodiment

Below in conjunction with specific embodiment the present invention is described in further detail, but these embodiment do not limit the scope of the invention.

Adopt weight-loss method that inhibiter of the present invention is estimated, concrete grammar is as follows: the 800mL corrosive medium is placed the 1L high-temperature high-pressure reaction kettle, add the metering inhibiter, the 20# carbon steel test piece that to clean then and accurately weigh is immersed in the corrosive medium with special hook, 240～340 ℃ of test temperatures, rotating speed 200rpm, carry out the inhibiter evaluation test under the condition of test period 48～96h, after the off-test, be cooled to room temperature and take out test piece, under ultrasonic wave, degreasing 5min is carried out in test piece with acetone, dry up after the taking-up, put into the cleaning of self-control washing lotion and remove test piece surface corrosion product or product film, after flushing with clean water, put into dehydrated alcohol and dewater twice,, be accurate to 0.0001g with weighing after the blower drying.The blank test working method is the same, does not just add any inhibiter in the process of the test.

Quality change according to before and after the test piece corrosion calculates erosion rate according to the following equation:

$V=\frac{(M_0-M)\×87.6}{S\×t\×\mathrm{\ρ}}$

V-erosion rate (weight-loss method is represented) in the formula, mm/a

m ₀-sample initial mass, mg;

m ₁Sample mass behind the-removal corrosion product, mg;

The S-specimen surface is long-pending, cm ²

The time that the t-corrosion is carried out, h.

The density of ρ-metal, g/cm ³

The inhibition efficiency of inhibiter:

η＝(V ₀-V ₁)/V ₀×100％

V ₀-erosion rate when not adding inhibiter;

V ₁Erosion rate during-adding inhibiter.

Wherein embodiment 1～embodiment 4 is the preparation of inhibiter, and embodiment 5～embodiment 7 is the inhibiter evaluation test.

Embodiment 1

(1) 156gC8～C10 alcohol mixture and the adding of 90g heavy aromatic solvent are had in the there-necked flask of condensing reflux and whipping appts, be warming up to 120 ℃, in 30 minutes, add the 90g thiophosphoric anhydride in batches, be warming up to 180 ℃ of reactions 4 hours then.

(2) 76g thiocarbamide and 103g diethylenetriamine are placed the there-necked flask that has condensing reflux and whipping appts, feed nitrogen, heat temperature raising to 170 ℃ reaction 6 hours is cooled to 70 ℃, adds step (1) reaction product, and isothermal reaction obtained inhibiter 1# in 1 hour.

Embodiment 2

(1) 130g n-Octanol and the adding of 100g heavy aromatic solvent are had in the there-necked flask of condensing reflux and whipping appts, be warming up to 120 ℃, in 30 minutes, add the 66g thiophosphoric anhydride in batches, be warming up to 170 ℃ of reactions 6 hours then.

(2) 76g thiocarbamide and 160g triethylene tetramine are placed the there-necked flask that has condensing reflux and whipping appts, feed nitrogen, heat temperature raising to 170 ℃ reaction 5 hours is cooled to 80 ℃, adds step (1) reaction product, and isothermal reaction obtained inhibiter 2# in 1 hour.

Embodiment 3

(1) 144g nonanol-and the adding of 120g heavy aromatic solvent are had in the there-necked flask of condensing reflux and whipping appts, be warming up to 120 ℃, in 30 minutes, add the 110g thiophosphoric anhydride in batches, be warming up to 160 ℃ of reactions 4 hours then.

(2) 76g thiocarbamide and 113g diethylenetriamine are placed the there-necked flask that has condensing reflux and whipping appts, feed nitrogen, heat temperature raising to 160 ℃ reaction 5 hours is cooled to 60 ℃, adds step (1) reaction product, and isothermal reaction obtained inhibiter 3# in 1 hour.

Embodiment 4

(1) 144g hexadecanol and the adding of 90g heavy aromatic solvent are had in the there-necked flask of condensing reflux and whipping appts, be warming up to 120 ℃, in 30 minutes, add the 60g thiophosphoric anhydride in batches, be warming up to 170 ℃ of reactions 7 hours then.

(2) 76g thiocarbamide and 200g tetraethylene pentamine are placed the there-necked flask that has condensing reflux and whipping appts, feed nitrogen, heat temperature raising to 180 ℃ reaction 5 hours is cooled to 80 ℃, adds step (1) reaction product, and isothermal reaction obtained inhibiter 4# in 1 hour.

Embodiment 5

Adopt white oil and crude naphthenic acid allotment acid number be the peracid oil of 10mgKOH/g as corrosive medium, estimate the corrosion inhibition of inhibiter, 280 ℃ of test temperatures, test period 48 hours, rotating speed 200rpm.Test-results sees Table 1.

Table 1 inhibiter evaluation result

As can be seen from Table 1, four kinds of inhibiter of synthetic all have the good restraining effect to naphthenic acid corrosion, and when add-on is not less than 30ppm, corrosion inhibition rate all can reach more than 90%.

Embodiment 6

Adopting Peng Lai crude oil is that (acid number of Peng Lai crude oil is 3.28mgKOH/g to corrosive medium, sulphur content 0.32%, nitrogen content 0.42%) 1# inhibiter of the present invention, SH9013 (piperazines), triphenyl phosphite, sulfonation nonyl phenol are estimated, 280 ℃ of test temperatures, test period 96 hours, test-results sees Table 2.

The evaluation result of the dissimilar inhibiter of table 2

As can be seen from Table 2, the slow reagent effect of synthetic of the present invention is significantly better than triphenyl phosphite, piperazines, sulfonation nonyl phenol and simple group thiophosphate inhibiter.

Embodiment 7

Corrosive medium is estimated the corrosion inhibition of 1# inhibiter in 240～340 ℃ of scopes, test period 48 hours, inhibiter add-on 100ppm with embodiment 5.Test-results sees Table 3.

The erosion rate of table 3 inhibiter 1# under differing temps

Temperature ℃	240	260	280	300	320	340
							Blank, mm/a	0.68	0.90	1.07	1.09	1.09	1.12
Erosion rate, mm/a	0.024	0.032	0.041	0.039	0.040	0.042
							Corrosion inhibition rate, %	96.5	96.4	96.2	96.4	96.3	96.25

As can be seen from Table 3, at 240 ℃～280 ℃ temperature sections, erosion rate changes greatly, the 0.041mm/a the when 0.024mmm/a during from 240 ℃ rises to 280 ℃, and erosion rate has increased 71%; At 280 ℃～340 ℃ temperature sections, along with test temperature raises, erosion rate slightly reduces earlier, increase gradually subsequently, but overall rangeability is less, and erosion rate maintains between 0.039mm/a～0.042mm/a.Test-results shows that in the most serious temperature section of naphthenic acid corrosion (280～340 ℃), this inhibiter has good corrosion mitigating effect.

Claims (8)

1. an inhibiter is characterized in that it being the mixture with two kinds of materials of general structure A and general structure B, and general structure A and general structure B are as follows:

R wherein ₁And R ₂Be the alkyl of C6～C18, R ₁With R ₂Carbon chain lengths can be the same or different; X is oxygen or sulphur, and having an X in each general formula at least is sulphur, and m is 1～4 integer.

2. inhibiter according to claim 1 is characterized in that described R ₁And R ₂Alkyl for C8～C10.

3. inhibiter according to claim 1 and 2 is characterized in that described R ₁With R ₂Carbon chain lengths identical.

4. a method for preparing the described inhibiter of claim 1 is characterized in that comprising the steps:

(1) Fatty Alcohol(C12-C14 and C12-C18) and organic solvent are placed reactor, heat to 120 ℃, add thiophosphoric anhydride in batches, be warming up to 160～190 ℃ then, reacted 3～7 hours, the generating structure general formula is the thiophosphatephosphorothioate compounds of C and D;

Wherein R, R ₁And R ₂Alkyl for C6～C18; R, R ₁With R ₂Carbon chain lengths can be the same or different; X is oxygen or sulphur, and having an X in each general formula at least is sulphur, and described Fatty Alcohol(C12-C14 and C12-C18) is straight or branched Fatty Alcohol(C12-C14 and C12-C18) or its mixture of C6～C18;

(2) equimolar thiocarbamide and polyethylene polyamine are placed a reactor with condensing works, stir and the feeding nitrogen protection, reacted about 150～180 ℃ 4～6 hours, the generating structure formula is the imidazolidine thione compounds of E;

Wherein n is 2～5 integer, described polyethylene polyamine be in diethylenetriamine, triethylene tetramine, tetraethylene pentamine, the five ethene hexamines any one;

(3) the imidazolidine thione compounds that obtains of thiophosphatephosphorothioate compounds that above-mentioned steps (1) is obtained and step (2) reacts under 60～80 ℃ of conditions and got final product in 1 hour.

5. the method for preparing inhibiter according to claim 4 is characterized in that described Fatty Alcohol(C12-C14 and C12-C18) is the Fatty Alcohol(C12-C14 and C12-C18) of C8～C10.

6. according to claim 4 or the 5 described methods that prepare inhibiter, it is characterized in that described R, R ₁With R ₂Carbon chain lengths identical.

7. according to claim 4 or the 5 described methods that prepare inhibiter, it is characterized in that described polyethylene polyamine is a diethylenetriamine.

8. the method for preparing inhibiter according to claim 6 is characterized in that described polyethylene polyamine is a diethylenetriamine.