Synthesis and catalytic studies of novel tetra sulfonylphenoxyls substituted Co(II), Cu(II), and Ni(II) phthalocyanines for the LPG sweetening

Abstract

Novel tetrasubstituted Co(II), Cu(II) and Ni(II) phthalocyanines with 4-sulfonylphenoxyl groups were synthesized by reacting 4-(4-sulfonylphenoxy) phthalonitrile with metal chlorides. And their structures were characterized by UV-visible absorption, Fourier-transform infrared spectrum, 1H NMR, and MALDI-TOF MS. These novel phthalocyanine complexes showed excellent solubility in water and alkali solutions. By using sodium propanethiol as model compound, the catalytic activity of these phthalocyanine derivatives was investigated for improving the catalytic sweetening of liquefied petroleum gas. It was found that the performance of Co(II) phthalocyanine complex was the best among the synthesized Co(II), Cu(II), and Ni(II) phthalocyanines, and it was also better than the commercialized sweetening catalyst of disufonated cobalt phthalocyanine. Conversion of sodium propanethiol catalyzed by Co(II) phthalocyanine complex could reach 95.2% after 50 min reaction and the catalytic conversion was 92.8% after the solution of Co(II) phthalocyanine complex had been storage for 11 days.