Natural gas engine oil and composite additive composition thereof

Abstract

The invention provides natural gas engine oil and a composite additive composition thereof, and the composite additive composition comprises: a detergent comprising magnesium sulfonate, calcium sulfonate and sulfurized calcium alkyl phenolate; the antioxidant comprises an amine type antioxidant and a phenol type antioxidant; the anti-wear agent is prepared from carbamic acid ester, phosphoric acid lauryl amine salt and tricresyl ester; a dispersant; the base number of the magnesium sulfonate is 395 to 420 mgKOH / g, the base number of the calcium sulfonate is 20 to 35 mgKOH / g, and the base number of the sulfurized calcium alkyl phenolate is 130 to 160 mgKOH / g. According to the natural gas engine oil, the sulfate ash content of the natural gas engine oil can be reduced, and the natural gas engine oil has relatively good oxidation resistance, detergency, dispersity, wear resistance and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a natural gas engine oil and a complex additive composition thereof, and belongs to the field of complex additives. BACKGROUND

[0002] As a substitute fuel engine, the engine using natural gas as fuel has high technical maturity and low cost, and is widely recognized in the industry. The natural gas-fueled national VI engine mostly adopts equivalent combustion technology, exhaust gas recirculation technology (EGR technology) and three-way catalyst technology (TWC technology), which can reduce the exhaust pollutants of the engine, such as significantly reducing the emission of particulate matter and CO2, and making the conversion efficiency of total hydrocarbons (THC) and nitrogen oxides (NOx) reach 100%, thereby meeting the relevant emission requirements of the engine.

[0003] However, the equivalent combustion technology, exhaust gas recirculation technology and three-way catalyst technology (three-way catalyst technology) increase the thermal load of the engine, making the high-temperature deposit problem of the natural gas engine oil more prominent, and also increasing the requirements for the oxidation resistance, detergency, dispersibility, anti-wear property and other properties of the natural gas engine oil. In addition, the natural gas engine oil meeting the national VI emission in the prior art often uses a natural gas engine oil with a sulfated ash content of 0.7-0.9%, mainly to easily achieve the 60,000 km oil change mileage requirement of the oil product. However, the excessively high sulfated ash content makes the engine prone to problems such as excessive deposits in the high-temperature region of the piston, the intake and exhaust valves during actual operation, resulting in excessive temperature of the intake and exhaust valves, valve melting, increased wear, blow-by and other hazards. Therefore, in order to further solve the problem of deposit formation, it is necessary to have a lower sulfated ash content of the oil product, stronger oxidation resistance and anti-wear ability of the oil product, and to achieve a higher oil change cycle. SUMMARY

[0004] The present application provides a natural gas engine oil and a complex additive composition thereof, which can be used in a natural gas engine oil, not only can reduce the sulfated ash content of the natural gas engine oil, but also make the natural gas engine oil have better oxidation resistance, detergency, dispersibility, anti-wear property and other properties, and achieve the 100,000 km oil change requirement.

[0005] The application provides a natural gas engine oil composite additive composition, comprising: a detergent, the detergent comprising magnesium sulfonate, calcium sulfonate, sulfated alkyl phenol calcium; in the natural gas engine oil composite additive composition, the mass percentage of the magnesium sulfonate is 0.5%-4.0%, the mass percentage of the calcium sulfonate is 5.0%-25.0%, and the mass percentage of the sulfated alkyl phenol calcium is 3.0%-10.0%; an antioxidant, the antioxidant comprising amine type antioxidant and phenolic antioxidant; in the natural gas engine oil composite additive composition, the mass percentage of the amine type antioxidant is 12.0%-25.0%, and the mass percentage of the phenolic antioxidant is 10.0%-20.0%; an anti-wear agent, the anti-wear agent comprising carbamate, dodecylamine phosphate salt and trimethylphenyl ester; in the natural gas engine oil composite additive composition, the mass percentage of the carbamate is 0.5%-3.0%, the mass percentage of the dodecylamine phosphate salt is 0.5%-3.0%, and the mass percentage of the trimethylphenyl ester is 1.0%-5.0%; a dispersant, in the natural gas engine oil composite additive composition, the mass percentage of the dispersant is 25.0%-60.0%; the base value of the magnesium sulfonate is 395-420 mgKOH / g, the base value of the calcium sulfonate is 20-35 mgKOH / g, and the base value of the sulfated alkyl phenol calcium is 130-160 mgKOH / g.

[0006] Optionally, in the natural gas engine oil composite additive composition, the mass percentage of the magnesium sulfonate is 1.5%-3.0%; and / or, the mass percentage of the calcium sulfonate is 10.0%-16.0%; and / or, the mass percentage of the sulfated alkyl phenol calcium is 5.0%-8.0%; and / or, the mass percentage of the amine type antioxidant is 15.0%-22.0%; and / or, the mass percentage of the phenolic antioxidant is 12.0%-18.0%; and / or, the mass percentage of the carbamate is 1.0%-2.0%; and / or, the mass percentage of the dodecylamine phosphate salt is 1.0%-2.0%; and / or, the mass percentage of the trimethylphenyl ester is 2.0%-3.5%; and / or, the mass percentage of the dispersant is 35.0%-45.0%.

[0007] Optionally, the amine type antioxidant comprises butyloctyl diphenylamine and N-phenyl-alpha-naphthylamine; in the natural gas engine oil composite additive composition, the mass percentage of the butyloctyl diphenylamine is 10.0%-20.0%, and the mass percentage of the N-phenyl-alpha-naphthylamine is 2.0%-5.0%.

[0008] Optionally, in the natural gas engine oil compound additive composition, the mass percentage of the butyl octyl diphenylamine is 12.0% to 18.0%; and / or, the mass percentage of the N-phenyl-α-naphthylamine is 3.0% to 4.0%.

[0009] Optionally, the phenolic antioxidant comprises a hindered phenolic ester.

[0010] Optionally, the carbamate comprises a dibutyl dithiocarbamate; and / or, the dodecylamine phosphate salt comprises a butyl isooctyl dodecylamine phosphate salt; and / or, the trimethylphenyl phosphate ester comprises a trimethylphenyl phosphate ester.

[0011] The present application provides a natural gas engine oil, which comprises, by mass percentage, 15%±0.5% of the natural gas engine oil compound additive composition as described above, 6.5% to 9.0% of a viscosity index improver, 0.2% to 0.5% of a pour point depressant, and the balance of a base oil.

[0012] Optionally, the viscosity index improver comprises an ethylene propylene copolymer.

[0013] Optionally, the pour point depressant comprises a polymethacrylate pour point depressant.

[0014] Optionally, the base oil comprises an API Group II base oil and / or an API Group III base oil.

[0015] The present application provides a natural gas engine oil and a compound additive composition thereof, which can be applied to a natural gas engine oil, so that the natural gas engine oil has a higher high-temperature deposit formation control ability, effectively solves the high-temperature deposit problem in the prior art, and also reduces the sulfated ash content of the natural gas engine oil, and improves the oxidation resistance, detergency, dispersibility, wear resistance and other properties of the natural gas engine oil, thereby prolonging the service life of the natural gas engine oil. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0017] This invention provides a natural gas engine oil and its composite additive composition. The natural gas engine oil composite additive composition includes: a detergent, comprising magnesium sulfonate, calcium sulfonate, and calcium alkylphenol sulfide; wherein the mass percentage of magnesium sulfonate in the natural gas engine oil composite additive composition is 0.5%–4.0%, the mass percentage of calcium sulfonate is 5.0%–25.0%, and the mass percentage of calcium alkylphenol sulfide is 3.0%–10.0%; and an antioxidant, comprising amine antioxidants and phenolic antioxidants; wherein the mass percentage of amine antioxidants in the natural gas engine oil composite additive composition is 12.0%–25.0%, and the mass percentage of phenolic antioxidants is 10%. 0.0%–20.0%; anti-wear agents, including urethane, dodecylamine phosphate, and tricresyl ester; in the natural gas engine oil compound additive composition, the mass percentage of urethane is 0.5%–3.0%, the mass percentage of dodecylamine phosphate is 0.5%–3.0%, and the mass percentage of tricresyl ester is 1.0%–5.0%; dispersant, in the natural gas engine oil compound additive composition, the mass percentage of dispersant is 25.0%–60.0%; the base value of magnesium sulfonate is 395–420 mgKOH / g, the base value of calcium sulfonate is 20–35 mgKOH / g, and the base value of alkylphenol calcium sulfide is 130–160 mgKOH / g.

[0018] According to the inventor's research and analysis, most antioxidants and anti-wear agents in existing natural gas engine oils use zinc dialkyl dithiophosphate. However, this increases the sulfate ash content of the natural gas engine oil. Furthermore, the sulfate ash content of existing China VI standard natural gas engine oils is generally 0.7%-0.9%, primarily to easily meet the 60,000 km oil change requirement. Excessive sulfate ash content leads to problems such as excessive deposits in the high-temperature areas of the piston and on the intake and exhaust valves during actual engine operation, resulting in excessively high intake and exhaust temperatures, valve melting, increased wear, and blow-by. In this embodiment of the invention, instead of using zinc dialkyl dithiophosphate as the antioxidant, amine-type and phenolic-type antioxidants are used. In the composition system of the natural gas engine oil composite additive composition (ultra-low ash natural gas engine oil composite additive composition) of this embodiment, the antioxidant system comprising amine-type and phenolic-type antioxidants gives the natural gas engine oil high antioxidant performance, effectively solving the oxidation durability problem of natural gas engine oil. Furthermore, this embodiment of the invention also uses an anti-wear agent comprising carbamate, dodecylamine phosphate, and tricresyl ester to replace zinc dialkyl dithiophosphate in the prior art. In the composition system of the natural gas engine oil composite additive composition of this embodiment, the anti-wear durability system comprising carbamate, dodecylamine phosphate, and tricresyl ester makes the natural gas engine oil more durable. Natural gas engine oils possess excellent anti-wear and durability properties, while further reducing sulfate ash content. Furthermore, by using a detergent system comprising magnesium sulfonate, calcium sulfonate, and calcium sulfide as a metal detergent, the high-temperature deposit problem caused by technologies such as stoichiometric combustion, exhaust gas recirculation, and three-way catalytic converters in natural gas engines can be addressed. For example, it effectively solves problems such as carbon deposits and varnish on pistons and valve systems. Moreover, the organic compounding of dispersants and detergents including magnesium sulfonate, calcium sulfonate, and calcium sulfide significantly improves the control of high-temperature deposit formation in natural gas engine oils, reducing the formation of high-temperature deposits and substantially decreasing deposits in high-temperature areas of pistons, intake and exhaust valves, thus preventing problems such as excessively high intake and exhaust temperatures, valve melting, accelerated wear, and blow-by. Simultaneously, it further enhances the oil's oxidation durability and anti-wear capabilities, achieving a longer oil change interval of 100,000 kilometers.

[0019] Therefore, the natural gas engine oil composite additive composition provided in this embodiment of the invention, when applied to natural gas engine oil, significantly reduces the sulfate ash content of the natural gas engine oil, effectively solves the problem of high-temperature deposits in natural gas engine oil, and also gives the natural gas engine oil better antioxidant, detergency, dispersibility, and anti-wear properties. Since the sulfate ash content, antioxidant, detergency (high-temperature detergency), anti-nitrification, anti-wear, and high-temperature deposit formation control capabilities of natural gas engine oil all affect its service life, the natural gas engine oil composite additive composition of this embodiment of the invention can extend the service life of natural gas engine oil to 100,000 kilometers, completely solving the problem of short service life of natural gas engine oil under low sulfate ash conditions.

[0020] In some embodiments, the above-described natural gas engine oil composite additive composition is applied to API Group II base oils and / or API Group III base oils to obtain a blended natural gas engine oil. This natural gas engine oil has an ultra-low sulfate ash content, specifically no more than 0.45%, and has passed Caterpillar 1M-PC engine bench tests and Program VIII engine bench tests, meeting the requirements for 100,000 kilometers of oil changes.

[0021] In addition to being used as an anti-wear agent, urethane esters can also be used as an antioxidant. When combined with antioxidants, including amine-type and phenol-type antioxidants, urethane esters form an antioxidant system that can replace zinc dialkyl dithiophosphate in existing technologies. This reduces the sulfate ash content of natural gas engine oils while giving them both high antioxidant durability and anti-wear durability.

[0022] In some embodiments, the magnesium sulfonate can be a high-alkalinity magnesium sulfonate detergent T107M, the calcium sulfonate can be a low-alkalinity calcium sulfonate detergent T104, and the alkylphenol sulfide calcium can be a low-alkalinity alkylphenol sulfide calcium detergent T115A.

[0023] In the composition system of the natural gas engine oil composite additive composition of this invention, the use of detergents including high-alkalinity magnesium sulfonate detergent T107M, low-alkalinity calcium sulfonate detergent T104, and low-alkalinity alkylphenol calcium sulfide detergent T115A as a metal detergent system can solve the problem of high-temperature deposits in natural gas engine oil caused by the use of stoichiometric combustion technology, exhaust gas recirculation technology, and three-way catalytic converter technology, reduce the sulfate ash content of natural gas engine oil, and enable natural gas engine oil to have good antioxidant, detergent, dispersant, and anti-wear properties, thereby extending the service life of natural gas engine oil.

[0024] The aforementioned dispersant may include polymeric dispersants, such as polymeric succinimide ashless dispersant, specifically polymeric succinimide ashless dispersant T161A. In the composition system of the natural gas engine oil composite additive composition of the present invention, after the dispersant is organically compounded with detergents including magnesium sulfonate, calcium sulfonate, and calcium alkylphenol sulfide, it can improve the ability to control the formation of high-temperature deposits in natural gas engine oil, reduce the formation of high-temperature deposits, purify natural gas engine oil, and reduce the sulfate ash content of natural gas engine oil, so that natural gas engine oil has good antioxidant, detergent, dispersant, and anti-wear properties, and extends the service life of natural gas engine oil.

[0025] Furthermore, in the composite additive composition of natural gas engine oil, the mass percentage of magnesium sulfonate is preferably 1.5% to 3.0%, the mass percentage of calcium sulfonate is preferably 10.0% to 16.0%, the mass percentage of alkylphenol calcium sulfide is preferably 5.0% to 8.0%, the mass percentage of amine antioxidant is preferably 15.0% to 22.0%, the mass percentage of phenolic antioxidant is preferably 12.0% to 18.0%, the mass percentage of carbamate is preferably 1.0% to 2.0%, the mass percentage of dodecylamine phosphate is preferably 1.0% to 2.0%, the mass percentage of tricresol ester is preferably 2.0% to 3.5%, and the mass percentage of dispersant is preferably 35.0% to 45.0%. This improves the sulfate ash content and high-temperature deposits of natural gas engine oil, and significantly enhances its antioxidant, detergency, dispersibility, and anti-wear properties, thus extending its service life.

[0026] In some embodiments, the aforementioned amine-type antioxidants include butyryldiphenylamine and N-phenyl-α-naphthylamine. In the natural gas engine oil composite additive composition, the mass percentage of butyryldiphenylamine is 10.0%–20.0%, preferably 12.0%–18.0%, and the mass percentage of N-phenyl-α-naphthylamine is 2.0%–5.0%, preferably 3.0%–4.0%. This can reduce the sulfate ash content of the natural gas engine oil, effectively solve the problem of high-temperature deposits in natural gas engine oil, and give the natural gas engine oil good antioxidant, detergency, dispersibility, and anti-wear properties, thus extending the service life of the natural gas engine oil.

[0027] The aforementioned butoctyl diphenylamine can specifically be butoctyl diphenylamine RHY057.

[0028] The aforementioned N-phenyl-α-naphthylamine can specifically be N-phenyl-α-naphthylamine T531.

[0029] In some embodiments, the phenolic antioxidant includes hindered phenolic esters, such as hindered phenolic ester RHY505. Under the composition system of the natural gas engine oil composite additive composition of the embodiments of the present invention, it helps to reduce the sulfate ash content of natural gas engine oil, effectively solves the problem of high-temperature deposits in natural gas engine oil, and enables the natural gas engine oil to possess good antioxidant, detergency, dispersibility, and anti-wear properties, thereby extending the service life of the natural gas engine oil.

[0030] In some embodiments, the carbamate includes dibutyl dithiocarbamate. In the composition system of the natural gas engine oil composite additive composition of this invention, on the one hand, dibutyl dithiocarbamate, dodecylamine phosphate, and tricresyl ester form an anti-wear durability system (oil anti-wear durability system), replacing the anti-wear system of zinc dialkyl dithiophosphate in conventional engine oils. This reduces the sulfate ash content of the natural gas engine oil while improving its anti-wear properties, thus achieving anti-wear durability of the natural gas engine oil. On the other hand, dibutyl dithiocarbamate, amine antioxidants, and phenolic antioxidants form an antioxidant system, further reducing the sulfate ash content of the natural gas engine oil while improving its antioxidant properties, completely solving the problems of oxidation durability and service life of natural gas engine oils, thereby extending the service life of the natural gas engine oil.

[0031] In some embodiments, the dodecylamine phosphate salt includes butyl isooctyl dodecylamine phosphate. In the composition system of the natural gas engine oil composite additive composition of this invention, butyl isooctyl dodecylamine phosphate, carbamate, and tricresol ester constitute an anti-wear durability system (oil anti-wear durability system), replacing the dialkyl dithiophosphate zinc anti-wear system in conventional engine oils. This reduces the sulfate ash content of the natural gas engine oil while improving its anti-wear properties, achieving anti-wear durability of the natural gas engine oil and helping to extend its service life.

[0032] In some embodiments, tricresyl ester includes tricresyl phosphate. In the composition system of the natural gas engine oil composite additive composition of this invention, tricresyl phosphate, carbamate, and dodecylamine phosphate form an anti-wear durability system (oil anti-wear durability system), replacing the anti-wear system of zinc dialkyl dithiophosphate in conventional engine oils. This reduces the sulfate ash content of the natural gas engine oil while improving its anti-wear properties, thus achieving anti-wear durability of the natural gas engine oil.

[0033] In some embodiments, the above-mentioned natural gas engine oil composite additive composition comprises, by weight percentage: 1.5% to 3% magnesium sulfonate, 10.0% to 16.0% calcium sulfonate, 5.0% to 8.0% calcium sulfide, 35.0% to 45.0% ashless dispersant succinimide, 12.0% to 18.0% butyl-octyl diphenylamine antioxidant, 3.0% to 4.0% N-phenyl-α-naphthylamine antioxidant, 12.0% to 18.0% hindered phenolic ester antioxidant, 1.0% to 2.0% dibutyl dithiocarbamate, 1.0% to 2.0% butyl isooctyl phosphate dodecylamine salt, and 2.0% to 3.5% tricresyl phosphate. This composite additive composition for natural gas engine oil can be used in natural gas engine oil to reduce the sulfate ash content of natural gas engine oil, while effectively solving the problem of high-temperature deposits in natural gas engine oil. It gives natural gas engine oil good antioxidant, detergency, dispersibility, and anti-wear properties, thus extending the service life of natural gas engine oil.

[0034] This invention also provides a natural gas engine oil, which comprises, by weight percentage: 15% ± 0.5% of the aforementioned natural gas engine oil composite additive composition, 6.5%–9.0% of a viscosity index improver, 0.2%–0.5% of a pour point depressant, and the balance being base oil. This natural gas engine oil has low sulfate ash content, effectively improving the problem of high-temperature deposit formation. It has a high base value and exhibits good antioxidant, detergency, dispersibility, and anti-wear properties, resulting in a long service life.

[0035] The aforementioned viscosity index improvers may include ethylene-propylene copolymers (OCP-type viscosity index improvers).

[0036] The aforementioned pour point depressants may include polymethyl methacrylate pour point depressants (PMA type pour point depressants).

[0037] The aforementioned base oils may include API Group II base oils and / or API Group III base oils, with API Group II and API Group III base oils being preferred. API Group II and API Group III base oils are two categories of base oils in the zinc-based lubricant base oil classification system jointly proposed by the American Petroleum Institute and the European Lubricant Industry Technical Association in the late 1990s.

[0038] In some embodiments, the natural gas engine oil comprises, by weight percentage: 15% ± 0.5% of the aforementioned natural gas engine oil composite additive composition, 6.5% to 9.0% of an OCP-type viscosity index depressant, 0.2% to 0.5% of a polyPMA-type pour point depressant, and the balance being base oil. This natural gas engine oil has a sulfate ash content not exceeding 0.45%, a base number as high as 8 mg KOH / g, and has passed the Caterpillar 1M-PC bench test (Cat. 1M-PC) and Program VIII engine test, meeting the oil change requirement for 100,000 kilometers.

[0039] The present invention will now be described in more detail through specific embodiments.

[0040] The sources of some of the raw materials used in the embodiments of the present invention are as follows:

[0041] Ashless polymeric dispersant: Ashless polymeric succinimide dispersant T161A;

[0042] High-alkalinity magnesium sulfonate: Alkalinity value is 402 mg KOH / g;

[0043] Low-alkalinity calcium sulfonate: Alkalinity value is 25.3 mg KOH / g;

[0044] Low-alkali-value alkylphenol calcium sulfide: alkali value is 155 mg KOH / g;

[0045] Phenolic antioxidant: Hindered phenolic ester RHY505;

[0046] Butyldiphenylamine: RHY057;

[0047] N-Phenylacetylamine: T531;

[0048] Tricresol phosphate: Tricresol phosphate T306;

[0049] API Group II and III base oils: PetroChina Group II and III base oils;

[0050] OCP viscosity index improver: RHY615 viscosity index improver;

[0051] PMA pour point depressant: Polymethyl methacrylate pour point depressant RHY808;

[0052] Commercially available medium-gray type natural gas engine oil: Kunlun G6 natural gas engine oil.

[0053] Test Example 1

[0054] I. Performance Testing of Natural Gas Engine Oil Composite Additive Composition (Ultra-Low Ash Natural Gas Engine Oil Composite Additive Composition)

[0055] The formulations of the natural gas engine oil composite additive compositions of Examples 1-5 and Comparative Examples 1 and 2 are shown in Table 1.

[0056] Table 1 Formulation of Natural Gas Engine Oil Composite Additive Composition

[0057]

[0058] Natural gas engine oils were prepared by combining the natural gas engine oil composite additive compositions of Examples 1-5 and Comparative Examples 1 and 2, API Group II base oil, API Group III base oil, OCP viscosity index depressant, and PMA pour point depressant according to the formulations shown in Table 2. Comparative Example 3 used commercially available medium-grey type natural gas engine oil.

[0059] Table 2. Formulation and performance test results of natural gas engine oils

[0060]

[0061]

[0062] Note: PDSC can be tested according to SH / T 0719 standard, micro-coking can be tested according to Q / SY RH 4012 standard, coking plate can be tested according to RH01 ZB4111 standard, heat pipe can be tested according to JPI-5S-55-99 standard, maximum non-seize load PB can be tested according to GB / T3142 standard, sintering load PD can be tested according to GB / T3142 standard, and wear scar diameter D392 can be tested according to GB / T3142. As shown in Table 2, the natural gas engine oil products blended with the natural gas engine oil composite additive compositions (ultra-low ash natural gas engine oil composite additive compositions) of Examples 1-5 at a dosage of 15% exhibit consistent performance in terms of detergency, anti-wear, dispersibility, and oxidation. Compared to the two comparative examples and commercially available products (commercially available medium-ash natural gas engine oils), they are superior in oxidation, detergency, dispersibility, and anti-wear performance.

[0063] Test Example 2

[0064] The natural gas engine oil (ultra-low ash natural gas engine oil) of Example 4 shown in Table 2 was subjected to Cat.1M-PC and Program VIII engine tests. The natural gas engine oil of Example 4 passed the Cat.1M-PC and Program VIII engine tests and can meet the oil change requirement of 100,000 kilometers. The specific results are shown in Table 3.

[0065] Table 3 Test results of natural gas engine oil in Example 4

[0066]

[0067]

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite additive composition for natural gas engine oil, characterized in that, include: The detergent comprises magnesium sulfonate, calcium sulfonate, and calcium alkylphenol sulfide; in the natural gas engine oil composite additive composition, the mass percentage of magnesium sulfonate is 0.5% to 4.0%, the mass percentage of calcium sulfonate is 5.0% to 25.0%, and the mass percentage of calcium alkylphenol sulfide is 3.0% to 10.0%. Antioxidants, including amine antioxidants and phenolic antioxidants; in the natural gas engine oil composite additive composition, the mass percentage of the amine antioxidant is 12.0% to 25.0%, and the mass percentage of the phenolic antioxidant is 10.0% to 20.0%. An anti-wear agent, comprising urethane, dodecylamine phosphate, and tricresyl ester; in the natural gas engine oil composite additive composition, the urethane has a mass percentage of 0.5% to 3.0%, the dodecylamine phosphate has a mass percentage of 0.5% to 3.0%, and the tricresyl ester has a mass percentage of 1.0% to 5.0%. The dispersant, in the natural gas engine oil composite additive composition, has a mass percentage content of 25.0% to 60.0%. The magnesium sulfonate has an alkalinity of 395–420 mg KOH / g, the calcium sulfonate has an alkalinity of 20–35 mg KOH / g, and the alkylphenol sulfide calcium has an alkalinity of 130–160 mg KOH / g.

2. The natural gas engine oil composite additive composition according to claim 1, characterized in that, In the natural gas engine oil composite additive composition, the magnesium sulfonate has a mass percentage content of 1.5% to 3.0%. And / or, the calcium sulfonate has a mass percentage content of 10.0% to 16.0%; And / or, the alkylphenol calcium sulfide has a mass percentage content of 5.0% to 8.0%; And / or, the amine antioxidant has a mass percentage content of 15.0% to 22.0%; And / or, the phenolic antioxidant has a mass percentage content of 12.0% to 18.0%; And / or, the carbamate content is 1.0% to 2.0% by mass; And / or, the mass percentage of the dodecylamine phosphate salt is 1.0% to 2.0%; And / or, the mass percentage of the tricresol ester is 2.0% to 3.5%; And / or, the mass percentage of the dispersant is 35.0% to 45.0%.

3. The natural gas engine oil composite additive composition according to claim 1, characterized in that, The amine-type antioxidants include butyryldiphenylamine and N-phenyl-α-naphthylamine; In the natural gas engine oil composite additive composition, the mass percentage of butyryldiphenylamine is 10.0% to 20.0%, and the mass percentage of N-phenyl-α-naphthylamine is 2.0% to 5.0%.

4. The natural gas engine oil composite additive composition according to claim 3, characterized in that, In the natural gas engine oil composite additive composition, the mass percentage of butyryldiphenylamine is 12.0% to 18.0%. And / or, the N-phenyl-α-naphthylamine has a mass percentage content of 3.0% to 4.0%.

5. The natural gas engine oil composite additive composition according to claim 1, characterized in that, The phenolic antioxidants include hindered phenolic esters.

6. The natural gas engine oil composite additive composition according to claim 1, characterized in that, The carbamates include dibutyl dithiocarbamates; And / or, the dodecylamine phosphate salt includes butyl isooctyl dodecylamine phosphate; And / or, the tricresol ester includes tricresol phosphate.

7. A natural gas engine oil, characterized in that, The natural gas engine oil comprises, by weight percentage: 15% ± 0.5% of the natural gas engine oil composite additive composition according to any one of claims 1 to 6, 6.5% to 9.0% of viscosity index improver, 0.2% to 0.5% of pour point depressant, and the balance being base oil.

8. The natural gas engine oil according to claim 7, characterized in that, The viscosity index improver includes ethylene-propylene copolymer.

9. The natural gas engine oil according to claim 7, characterized in that, The pour point depressant includes a polymethacrylate pour point depressant.

10. The natural gas engine oil according to claim 7, characterized in that, The base oils include API Group II base oils and / or API Group III base oils.

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