Refining of used oils using membrane- and adsorption-based processes

A method suitable for treating used oil to remove contaminants including ash and color contaminants therefrom to provide a purified oil product, the method comprising the steps of:

• (a) providing a porous inorganic membrane module having a high pressure side and a low pressure side, having a pore size in the range of 50 A to 10 um;
• (b) providing a body of oil to be treated;
• (c) heating said body of oil a temperature in the range of 50 to 250.degree. C. to provide heated oil;
• (d) introducing said heated oil to the high pressure side of said membrane module to provide an oil permeate on the low pressure side and an ash rich concentrate on the high pressure side, the oil in the high pressure side maintained at a pressure in the range of 10 to 250 psi thereby separating ash in said oil from said oil permeate;
• (d) contacting said oil permeate with an adsorbent at a temperature of less than 120.degree. C. to remove one of color and odor from said oil permeate to provide a purified oil product, the adsorbent selected from at least one of the adsorbents from the group consisting of activated alumina, zeolite, silica gel, anionic clay, and cationic clay;
• and thereafter
• (e) periodically regenerating said adsorbent.

In an improved method of treating oil to remove color and odor therefrom, wherein said oil is first treated to remove ash to provide treated oil having lowered ash content, the improvement including:

• (a) introducing said oil to the high pressure side of an inorganic membrane module and producing an oil permeate a low pressure side of said membrane module;
• and
• (b) contacting said oil permeate having a temperature of less than 120.degree. C. and having a lowered ash content with an adsorbent to remove at least one of color and odor, the adsorbent selected from at least one of adsorbents from the group consisting of activated alumina, zeolite, silica gel, anionic and cationic clay;
• and thereafter
• (c) periodically regenerating said adsorbent.

In an improved method of treating oil to remove color and odor therefrom, wherein said oil is first treated to remove ash to provide treated oil having lowered ash content, the improvement including:

• (a) introducing said oil to the high pressure side of an inorganic membrane module and producing an oil permeate at a low pressure side of said membrane module;
• (b) contacting said oil at a temperature less than 120.degree. C. and having lowered ash content with an adsorbent to remove at least one of color and odor, the adsorbent selected as cationic clay;
• and
• (c) regenerating said cationic clay by exposing said adsorbent to a temperature in the range of 300 to 800.degree. C. in the presence of air.