Process for in-situ synthesis of dispersion ZnO—TiO2 nanoparticles in oil

Patent metadata

Field	Value
Publication number	US-10633609-B2
Application number	US-201815980900-A
Country	US
Kind code	B2
Filing date	May 16, 2018
Priority date	May 16, 2017
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

The present invention provides a process for in situ synthesis of dispersion of ZnO and TiO2 nanoparticles in an oil medium, wherein the process comprises: (a) providing layered basic zinc hydroxide (LBZ) in an oil medium, containing a dispersant, (b) providing a titanium precursor in the oil medium to obtain a mixture, (c) hydrolyzing the mixture to obtain a suspension, and (d) decomposing the suspension to obtain a dispersion of mixture of ZnO and TiO2 nanoparticles. The present invention also provides an oil dispersion comprising dispersant stabilized mixture of zinc oxide and titanium dioxide nanoparticles were synthesized through this process. The dispersion contains up to 2.5 Wt % metals loading balanced with dispersant and base oil or dispersant alone. Addition of this dispersion to oil of lubricating viscosity improves the anti-wear property and resulting a low SAPS formulation.

First claim

The invention claimed is:

1. A process for in situ synthesis of dispersion of ZnO and TiO 2 nanoparticles in an oil medium, wherein the process comprises:
(a) providing layered basic zinc hydroxide (LBZ) in an oil medium, containing a dispersant,
(b) providing a titanium precursor in the oil medium to obtain a mixture,
(c) hydrolyzing the mixture to obtain a suspension, and
(d) decomposing the suspension to obtain a dispersion of mixture of ZnO and TiO 2 nanoparticles.

2. The process of claim 1 , wherein the titanium precursor is a titanium tetra alkoxide precursor having formula Ti(OR) 4 , wherein R is C1 to C4 alkyl group and the titanium tetra alkoxide precursors is selected from the group comprising of titanium tetra isopropoxide, titanium tetrabutoxide, titanium tetra ethoxide, and titanium tetra methoxide.

3. The process of claim 1 , wherein the hydrolysis is achieved by the water existing in the form of hydrate within LBZ and the hydrolysis of mixture comprises refluxing the mixture of step (b) to hydrolyze titanium precursor to obtain a colloidal suspension containing titanium hydrous oxide in oil containing LBZ and dispersant.

4. The process of claim 1 , wherein the decomposition comprises heating to 120-150° C. to obtain a dispersion of mixture of ZnO and TiO 2 nanoparticles, along with dispersant and residual anions.

5. The process of claim 1 , wherein the in situ prepared nanoparticles of ZnO and TiO 2 are stabilized by dispersant in the oil medium, wherein the dispersant is ashless dispersant.

6. The process of claim 1 , wherein the dispersant is present in the concentration range of 50-75 wt % or 50-65 wt % and the dispersant is oil soluble and free from phosphorus and sulfur.

7. The process of claim 4 , wherein the dispersant is nitrogen substituted long chain alkenyl succinimide dispersant and selected from the group consisting of Polyisobutylene Succinimides (PIBSI), oil soluble fatty acid, sorbitan ester, and oil soluble carboxylic acids.

8. The process of claim 1 , wherein step (a) comprises dispersing LBZ in a C1-C3 alcohol and adding to oil medium containing 40-60% of dispersant.

9. The process of claim 1 , wherein providing a titanium precursor in said oil medium to obtain a mixture comprises stirring the mixture of step (a) continuously at 200-1500 RPM and adding stoichiometric amount of titanium tetra alkoxide precursor resulting Ti content of 3% by weight.

10. The process of claim 1 , wherein the step (c) comprises:
(i) hydrolyzing the titanium tetra alkoxides precursor by the water molecules of layered basic zinc hydroxide (LBZ) in oil medium comprising dispersant to give a colloidal suspension comprising titanium hydrous oxide in oil containing LBZ and dispersant; and
(ii) evacuating the colloidal suspension of step (i) and followed by heating to 120-150° C. for 45 to 90 minutes to trigger the LBZ decomposition to ZnO and TiO 2 formation from titanium hydrous oxides to give a clear dispersion of ZnO nanoparticles in the oil medium along with nanoparticles of TiO 2 , dispersant and residual anions.

11. The process of claim 6 , wherein the nanoparticles of TiO 2 is prepared by the presence of 2 moles of H 2 O within LBZ and ZnO nanoparticles is prepared by the decomposition of LBZ within the oil medium containing stabilizing agents and nano TiO 2 .

12. The process of claim 6 , wherein in the oil medium the nanoparticles of TiO 2 and ZnO are stabilized by dispersant in the concentration range in weight percent 50-75% or 50-65%, wherein dispersant is ashless dispersant.

13. The process of claim 7 , wherein the ashless dispersant is oil soluble compounds containing polymeric hydrocarbon structure and polar functional groups that stabilize nanoparticles.

14. The process of claim 7 , wherein the ashless dispersant is nitrogen substituted long chain alkenyl succinimides dispersant and selected from the group consisting of Polyisobutylene Succinimides (PIBSI), oil soluble fatty acid, sorbitan ester or oil soluble carboxylic acids.

15. The process of claim 6 , wherein in step (i) the LBZ is dispersed in a C1-C3 alcohol and added to oil containing 40-60 wt % of dispersant before adding the titanium tetra alkoxide precursor to obtain a mixture and then the mixture is refluxed and during refluxing period the moles of water molecule hydrolyze titanium tetra alkoxide to give a colloidal suspension containing titanium hydrous oxide in oil containing LBZ and dispersant.

16. The process of claim 6 , wherein the oil is selected from the group comprising of base oil, process oil, mineral lubricating oils, solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types, polyalphaolefins (PAOs) derived from monomers having from 4 to 30 carbon atoms having a viscosity in the range from 1.5 to 150 mm 2 /s (cSt) at 100° C., esters of dicarboxylic acids with a variety of alcohols, or a mixture thereof.

17. The process of claim 6 , wherein LBZ having formula Zn 5 (OH) 8 (X) 2 .2H 2 O and X is anions and selected from a group comprising of Cl, NO 3 , Br, I, and CH 3 COO − .

18. The process of claim 6 , wherein the layered base zinc (LBZ) is prepared by the process comprising:
(a) dissolving a Zinc salt comprising of zinc acetate dihydrate in an alcoholic solvent and heating to 90-120° C. for 40 minutes to 24 hours to obtain a suspension;
(b) centrifuging the suspension as obtained in step (a) and washing with deionized water to precipitate layered base zinc (LBZ) having 2 moles of water in the form of hydrate.

Assignees

• Indian Oil Corp Ltd

Inventors

• VIJAYARAJ Munusamy
• Hait Samik Kumar
• Sastry Madhira Indu Sekhara
• RAMAKUMAR Sankara Sri Venkata

Classifications

• C01G23/053

  Producing by wet processes, e.g. hydrolysing titanium salts · CPC title

• B82Y99/00

  Subject matter not provided for in other groups of this subclass · CPC title

• C10N2050/015

  Dispersions of solid lubricants · CPC title

• C10N2040/25

  Internal-combustion engines · CPC title

• C10N2030/06

  Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure · CPC title