Noble metal catalysts for the hydrodeoxygenation and hydrodenitrogenation of fatty amides

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

The development of active catalysts for simultaneous hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) is important for the processing of renewable feedstocks to fuels. In this thesis, the hydrotreatment of fatty amides and their derivatives was studied on supported noble metal catalysts. Studies on competitive HDO and HDN reactions in the co-hydrotreatment of palmitic acid and 1-tetradecylamine over Pt/ZrO2 indicated that HDO proceeded more efficiently than HDN on all studied feed compositions. The preferential HDO of the oxygen-containing compounds and formation of secondary amides and amines via condensation reactions inhibited the HDN of 1-tetradecylamine in the co-hydrotreating experiments. The hydrotreatment of n-hexadecanamide was studied in a batch reactor at 300 °C and 80 bar H2, over Pt catalysts supported on SiO2, Al2O3, SiO2-Al2O3, TiO2, Nb2O5, ZrO2 and CeO2-ZrO2, as well as Pd, Rh, Ru and Ni supported on ZrO2. The Lewis acid properties of the support influenced the activity and selectivity towards the initial n-hexadecanamide conversion route, and the conversion of the oxygen-containing intermediate products. The oxygen-containing intermediate products were converted particularly efficiently on Pt/CeO2-ZrO2, which was attributed to the weak Lewis acid sites on the reducible support. The active metal influenced the activity and selectivity for condensation reactions and for the formation of n-pentadecane and n-hexadecane from the intermediate products. HDO proceeded more efficiently than HDN on the studied catalysts. Finally, monometallic and bimetallic catalysts supported on CeO2-ZrO2 were prepared, characterized and tested for their activity in the hydrotreatment of n-hexadecanamide. The catalytic properties of the bimetallic catalysts were markedly different compared to the corresponding monometallic catalysts, which, based on the characterization, appeared to be due to interactions between the active metals. The combination of Ni with a noble metal was particularly beneficial for the catalytic activity, and the RuNi/CeO2-ZrO2 catalyst exhibited the highest activity and selectivity towards the formation of n-pentadecane out of the catalysts studied in this thesis. The results of this thesis brought new insights into the influence of the catalyst composition on the activity, selectivity and reaction network in the hydrotreatment of fatty amides to n-paraffins.
Translated title of the contributionJalometallikatalyytit amidien vetykäsittelyssä
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Puurunen, Riikka, Supervising Professor
  • Karinen, Reetta, Thesis Advisor
  • Tiitta, Marja, Thesis Advisor, External person
Publisher
Print ISBNs978-952-64-1760-8
Electronic ISBNs978-952-64-1761-5
Publication statusPublished - 2024
MoE publication typeG5 Doctoral dissertation (article)

Keywords

  • hydrotreatment
  • hydrodeoxygenation
  • hydrodenitrogenation
  • amide
  • noble metal catalyst

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