CpRu(CO)2(BF4) and [CpFe(CO)2(THF)]+ on mesoporous silica as adsorbents for the removal of dibenzothiophenes from hydrocarbon solutions

Abstract

The complexes, CpRu(CO)₂(BF₄) and [CpFe(CO)₂(η²-2-methylpropene)][BF₄], react with dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-Me₂DBT) to give [CpRu(CO)₂(DBT)][BF₄] and [CpFe(CO)₂(4,6-Me₂DBT)][BF₄], whose structures were established by X-ray diffraction studies. The same types of products are obtained when dibenzothiophenes react with CpRu(CO)₂(BF₄) and [CpFe(CO)₂(THF)][BF₄] that are adsorbed on the mesoporous silica SBA-15. DRIFT and XPS studies indicate that CpRu(CO)₂(BF₄) and [CpRu(CO)₂(DBT)][BF₄] are adsorbed on the SBA-15 by hydrogen-bonding of the BF₄⁻ anions to surface Si–O–H groups. CpRu(CO)₂(BF₄)/SBA-15 removes 99% of the DBT in a 45% toluene/55% hexanes simulated petroleum feedstock. This solid phase extractant is less successful for sterically-hindered 4,6-Me₂DBT, as only 72% of it is removed. The results show that CpRu(CO)₂(BF₄) can be immobilized by adsorption on mesoporous silica and that it reacts with dibenzothiophenes in the adsorbed form, CpRu(CO)₂(BF₄)/SBA-15, in much the same way that it reacts in solution.