Alternative diesel fuels with high hydrogen content in their molecular structures

Abstract Alternative fuel components have a continuously growing use worldwide. Hydrocarbons with high hydrogen to carbon ratio in their molecular structures are the most suitable alternative fuels. In this paper the special hydrocracking of waste fatty acids and waste lard to paraffin mixtures over sulfided NiMoP/Al 2 O 3 is presented. The effect of feedstock additives was investigated on the catalyst performance, such as activity, selectivity, product yield and catalyst lifetime. It was concluded that coke precursors, which were formed from olefinic components reduced the catalyst performance. Olefins were generated as intermediates of hydrocracking but could be present also in the feedstocks. Based on the results it was also concluded that application of amine and phenol type additives in the feedstocks inhibited the formation of coke precursors and coke. Results of catalytic tests having length of ca. 1000 h were compared. Applying 200 mg/kg additive in favorable combination resulted in about 21–37 wt% increase in the yield of target products relative to that using feedstock without additives. The obtained target products were rich in n-paraffins and represented diesel blending components of >85 cetane number. Various ideas are proposed for the utilization of the obtained bio-paraffin mixture.