Catalyst – solid sorbent – or support therefor: product or process – Regenerating or rehabilitating catalyst or sorbent – Treating with a liquid or treating in a liquid phase,...
Reexamination Certificate
2001-02-21
2003-10-21
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Regenerating or rehabilitating catalyst or sorbent
Treating with a liquid or treating in a liquid phase,...
Reexamination Certificate
active
06635595
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a novel and simple process for the simultaneous regeneration of spent bleaching earth and conversion of adsorbed oil to alkyl esters of C
1
to C
8
carbon atoms by using alcohols. The present invention particularly relates to an improved process for the recovery of oil and its insitu conversion to methyl esters. The regenerated spent bleaching earth is further activated at 120-500° C. for 2-6 hours in a muffel furnace. The regenerated and activated earth can be reused for the bleaching of vegetable oils. The alkyl esters obtained after distillation find use as oleochemical feedstock.
BACKGROUND OF THE INVENTION
The refining of oils requires several steps to remove components that are harmful to health, or that are deleterious to storage quality. The classical steps for this purpose are de-gumming, neutralizing, bleaching and deodorizing. Bleaching with active clay is an essential step in refining of vegetable oils. The bleaching process removes undesirable substances such as soap residues, traces of heavy metals, pesticide residues and residues of phosphorus compounds etc. apart from its main purpose of removal of coloring matter like carotenoids and chlorophyll pigments. Bleaching process is carried out by using heat, hydrogen, chemical additives or by adsorption on solids. Adsorptive bleaching not only removes the coloring matter but also fulfils the other requirements of the bleaching process. Bleaching clays employed for this process are alumino silicates containing magnesium, calcium and iron in varying proportions. These clays are subjected to acid treatment, which replaces the cations by protons, thereby increasing the internal surface area and the adsorptive capacity. Bleaching of vegetable oils is carried out at a dosage of 1-3% and the current worldwide production of>60 million tons of oils is accompanied by production of spent clay containing 20-40% oil estimated at 600,000 tones. The disposal of spent bleaching clay from the vegetable oil processing industry is a problem of growing importance. Disposal of the spent earth by incineration, inclusion in animal feeds, land filling methods, or concrete etc. is generally practiced. It was a general practice to recover the fatty matter from the earth and discard the deactivated earth. The constant change in environmental legislation and the growing importance of safety in the disposal techniques has led to many restrictions in solid waste management. The earlier research on spent clay reclamation focused on the oil left in the spent clay and the clay itself was not regenerated for reuse. The recovered oil was used for industrial purposes. Recent studies are focusing not only on recovery of left over oil in the spent clay but also on regeneration of spent bleaching earth for reuse. The recovery of oil and reuse of spent bleaching earth are the areas where great opportunity exists for cost saving in the oil processing industry.
PRIOR ART DISCUSSION
There are many patented methods and published literature available on regeneration of spent earth. Different methods proposed for the recovery of oil from spent earth have been reviewed by Kaufmann and Mukharjee (Fette, Seifen, Anstrichm. 1967, 69, 463) and recovery by water separation and solvent extraction were the most commonly reported methods. Thermal regeneration of spent alumina used for bleaching of cottonseed oil was done at 400-700° C. followed by re-moisturizing the earth to ≈10%. Spent earth from the bleaching of edible oils is revived by washing with an organic solvent preferably acetone or methyl ethyl ketone. Kalam and Joshi (Journal of Am. oil Chem. Society, 1988, 65, 1917-1921) studied regeneration of deoiled spent earth in aqueous medium at a relatively lower temperature (170-270° C.) in an autoclave. They achieved about 81% regeneration (reduction in red color only). Thus, the mechanism of regeneration was explained as, desorption of adsorbate from the surface of the adsorbent, intra-particle diffusion within pores to the outer surface of the adsorbent, mass transfer from adsorbent to the liquid bulk and finally possible degradation of adsorbate in liquid bulk. Kalam and Joshi (Journal of Am. oil Chem. Society, 1988, 65, 1536-1540) also reported regeneration of de-oiled spent earth by wet oxidation method using molecular oxygen at elevated temperatures of 125-350° C. and pressure of 1-20 Mpa. in an autoclave. Thus chemical regeneration method was claimed to be clean, compact and cost effective. It proceeds via fragmentation of larger molecules into smaller molecules and finally oxidation to carbondioxide and water. Waldmann and Eggers studied de-oiling of bleaching clay by high-pressure extraction with carbondioxide as a solvent (Journal of Am. oil Chem. Society, 1991, 68, 922-930). The authors in their investigations compared the extractability of two different types of bleaching clays with carbondioxide as a solvent aiming a complete separation of the oil from the adsorbent and reuse of the later. Their results showed that oil of good quality could be recovered and the bleaching clay still has an activity of approximately 50% of fresh clay. The degree of extraction of oil for different experiments was in the range of 93 to 97%. There are many patents for the regeneration of spent bleaching earth which include an oxidation step in their process (GB Z189, 233, EP 05,29555, U.S. Pat. Nos. 5,256,613, 5,358,915, 5,468,701). Nebergall (INFORM, 1996, 7, 206-211) in his article on “Spent bleaching earth regeneration—commercial scale results” reviewed various pretreatment, extraction and post-treatment methods. He concluded that the autoclave extracted de-oiled clay produced regenerated clay far superior to that of the fresh clay. Thus all further work was done on various systems of oxidation and reactivation following an initial autoclave extraction on pilot-plant level for commercial viability. In this process due to the high temperature of processing in the autoclave, most of the adsorbed vegetable oil was converted to glycerol and free fatty acids. This step of the process recovered ≈65-70% of the organics present in the spent bleaching earth. The organics remaining on the bleaching earth i.e. chlorophyll pigments and carotenoids are burned onto the active sites by the oxidizing agent whereby they are reduced to a type of activated carbon resulting in superior performance of pilot plant regenerated clay than fresh clay. Surface—and pore—structures of de-oiled acid—and heat treated spent bleaching clays were studied after de-oiling by extraction with organic solvents (J. Am. Oil Chem. Soc., 1997, 74, 963-970). Acid and then heat treatment regenerated the de-oiled clays. Acidified heat-treated de-oiled samples had larger surface areas and greater pore volumes than fresh clay samples. Thus acid and heat treatments removed substances adsorbed in the pores that were not removed by solvents or carbondioxide extraction. A slight modification to the above process was the regeneration of spent bleaching earth first by thermal processing followed by acid treatment which resulted in the regenerated adsorbent with better properties (J. Chem. Technol. Biotechnol, 2000, 75, 773-776).
U.S. Pat. Nos. 4,469,805 and 3,472,786 disclose a process for removal of organic, polar type and nitrogen containing impurities from spent clay by percolating liquid methanol through a bed of spent clay. But in both cases, the spent clay was used to purify petroleum and not edible oil. In both cases, the oil present in the mixture was not converted into corresponding ester. However, the essential and non-obvious aspect of the present invention is the use of alcohol and the simultaneous conversion of the acids into its corresponding esters within a temperature range of 110° to 270° C. The treatment of spent clay in organic phase at high temperatures and moderate pressure results in simultaneous regeneration of clay and conversion of oils into ester. The high temperatures and efficient stirring increases the solubility of adsorbed species
Kaimal Thengumpillil Narayana Balagopala
Laxmi Ayyagari Ananta
Ramalinga Bandi
Vijayalakshmi Penumarthy
Council of Scientific & Industrial Research
Johnson Edward M.
Pennie & Edmonds LLP
Silverman Stanley S.
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