Nickel amine complexes as structure-directing agents for aluminophosphate molecular sieves: a new route to supported nickel catalysts

R Garcia, T D Coombs, I J Shannon, P A Wright, P A Cox

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Open framework aluminophosphates (AlPOs) with the framework types CHA, AFI, AEI, SAS and SAV have been prepared using nickel complexes of linear and macrocyclic polyamines as structure-directing agents: The [Ni(diethylenetriamine)(2)](2+) complex has been used to prepare aluminophosphate-fluoride versions of the CHA and AFI topologies as well as substituted metalloaluminophosphates (MAPOs) and silicoaluminophosphates (SAPOs) with the CHA topology; the nickel complex of the macrocycle 1,4,7,10-tetraazacyclododecane (cyclen) acts as a structure-directing agent for MAPO-18 (AEI topology), and the nickel complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam) and 1,4,8,11-tetramethylcyclam direct the formation of STA-6 (SAS topology) or STA-7 (SAV topology) depending on the inorganic composition and the type of amine added as a cobase to control the synthesis pH. Magnesioaluminophosphate-5 (AFI topology) containing complexed nickel has been prepared using a novel mixed azamacrocycle-quinuclidinium cation as a structure-directing agent. Nickel complex-containing AlPOs and SAPOs with the CHA framework topology have been calcined and used as catalysts for the conversion of butane over the temperature range 375-575 degreesC with a WHSV of 1.8 h(-1). The inclusion of nickel increases the rate of conversion and also changes the composition of the products from the full C1-C4 range to pure methane. This behavior is attributed to the reduction of Ni(II) to finely dispersed supported nickel particles.

Original languageEnglish
Pages (from-to)115-124
Number of pages10
JournalTopics in Catalysis
Volume24
Issue number1-4
DOIs
Publication statusPublished - Oct 2003

Keywords

  • microporous aluminophosphates
  • nickel complexes
  • supported nickel catalysts
  • CRYSTALLIZATION

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