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ص لبحوث العلمية الفائزة بجائزة
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عدد خا
مجلة النفط والتعاون العربي
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العدد
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أربعون
المجلد الثالث و ال
Re-refining of Used Lubricating Oil and its Economic and Environmental Implications
29
4.8 PROP technology
The PROP (Phillips Re-refined Oil Process) technology, developed by the Phillips
Petroleum Company, combines chemical demetallisation and hydrogenation to remove
contaminants from the used lube oil.
4.8.1
Process description
The basic steps of the process are as follows:
Demetallization and contaminants removal:
The process begins by mixing an aqueous solution of diammonium phosphate with
heated used lube oil to reduce the metal content of the oil. Chemical reactions lead to
formation of metallic phosphates, which are subsequently removed by filtration. The
remaining oil is then flashed to remove light hydrocarbons, gasoline, and water.
Hydrogenation:
Next, the oil is mixed with hydrogen and percolated through a bed of clay, and passed
over a Ni/Mo catalyst in the hydrogenation reactor. The adsorption step removes the
remaining traces of compounds which might poison the catalyst. During the
hydrogenation process, sulphur, oxygen, chlorine and nitrogen-containing compounds
are removed and the oil's color is thereby improved.
The PROP process flow diagram is depicted in Figure 15.
4.8.2
Process features and drawbacks
The major solid by-product is described as neutral phosphate material with no potential
disposal problem. This by-product can be safely disposed of in a landfill. Liquid stream
byproducts relate to light ends and heavy gasoline which can be used as fuel. However,
the used catalyst is typically treated as hazardous waste. The spent catalyst represents a
hazardous waste product.