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Denickling of fatty acid pitch

Aly, Gharib LU ; Stenström, Stig LU ; Bertilsson, F and Beijer, M (1993) In Journal of the American Oil Chemists Society 70(2). p.193-197
Abstract
Unsaturated fatty acids are usually hydrogenated with a nickel catalyst. As a side reaction, nickel dissolves in the fatty acids and forms nickel soaps. On refining the crude fatty acid feedstock by distillation, these nickel soaps are enriched in the bottom fraction (pitch) to a concentration range of 2,500-5,500 ppm. With a heat value comparable to heavy fuel oil, the pitch has been used as fuel. However, due to new environmental restrictions, the nickel concentration must be considerably reduced to limit gas emission of nickel. In this study, solvent extraction was investigated as a separation method for denickling of this valuable oleochemical by-product. At a temperature of 80-degrees-C, the nickel content in the pitch was reduced... (More)
Unsaturated fatty acids are usually hydrogenated with a nickel catalyst. As a side reaction, nickel dissolves in the fatty acids and forms nickel soaps. On refining the crude fatty acid feedstock by distillation, these nickel soaps are enriched in the bottom fraction (pitch) to a concentration range of 2,500-5,500 ppm. With a heat value comparable to heavy fuel oil, the pitch has been used as fuel. However, due to new environmental restrictions, the nickel concentration must be considerably reduced to limit gas emission of nickel. In this study, solvent extraction was investigated as a separation method for denickling of this valuable oleochemical by-product. At a temperature of 80-degrees-C, the nickel content in the pitch was reduced from 2,900 ppm to 4 ppm in three extraction steps by means of 1 wt% citric acid in water. Based on experimental results, a preliminary process flowsheet is presented consisting of extraction, stripping, acid washing and electrolysis. An economic analysis, performed on the extraction process and a process based on direct combustion followed by electrostatic precipitation revealed that direct combustion is economically more advantageous. However, the compatibility of the extraction alternative can be considerably improved by process optimization. The type and concentration of the stripping and acid washing agents, phase ratios, temperature, ionic strength and the equilibrium pH of the aqueous and acid phases are important process parameters that should be considered in the optimization process. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
DENICKLING, FATTY ACIDS, PITCH, SOLVENT EXTRACTION
in
Journal of the American Oil Chemists Society
volume
70
issue
2
pages
193 - 197
publisher
The American Oil Chemists' Society
external identifiers
  • wos:A1993KL81700015
  • scopus:0027542612
ISSN
0003-021X
DOI
10.1007/BF02542625
language
English
LU publication?
yes
id
ae0111c9-9d4b-4708-847e-a6b2a91b77d5 (old id 3914100)
date added to LUP
2013-07-01 11:18:44
date last changed
2017-01-01 04:39:10
@article{ae0111c9-9d4b-4708-847e-a6b2a91b77d5,
  abstract     = {Unsaturated fatty acids are usually hydrogenated with a nickel catalyst. As a side reaction, nickel dissolves in the fatty acids and forms nickel soaps. On refining the crude fatty acid feedstock by distillation, these nickel soaps are enriched in the bottom fraction (pitch) to a concentration range of 2,500-5,500 ppm. With a heat value comparable to heavy fuel oil, the pitch has been used as fuel. However, due to new environmental restrictions, the nickel concentration must be considerably reduced to limit gas emission of nickel. In this study, solvent extraction was investigated as a separation method for denickling of this valuable oleochemical by-product. At a temperature of 80-degrees-C, the nickel content in the pitch was reduced from 2,900 ppm to 4 ppm in three extraction steps by means of 1 wt% citric acid in water. Based on experimental results, a preliminary process flowsheet is presented consisting of extraction, stripping, acid washing and electrolysis. An economic analysis, performed on the extraction process and a process based on direct combustion followed by electrostatic precipitation revealed that direct combustion is economically more advantageous. However, the compatibility of the extraction alternative can be considerably improved by process optimization. The type and concentration of the stripping and acid washing agents, phase ratios, temperature, ionic strength and the equilibrium pH of the aqueous and acid phases are important process parameters that should be considered in the optimization process.},
  author       = {Aly, Gharib and Stenström, Stig and Bertilsson, F and Beijer, M},
  issn         = {0003-021X},
  keyword      = {DENICKLING,FATTY ACIDS,PITCH,SOLVENT EXTRACTION},
  language     = {eng},
  number       = {2},
  pages        = {193--197},
  publisher    = {The American Oil Chemists' Society},
  series       = {Journal of the American Oil Chemists Society},
  title        = {Denickling of fatty acid pitch},
  url          = {http://dx.doi.org/10.1007/BF02542625},
  volume       = {70},
  year         = {1993},
}