Enhanced activity of CuO/ZnO catalyst on the decomposition of dimethylhexane-1,6-dicarbamate into dimethylhexane-1,6-diisocyanate

Jinsung Kim, Cheonwoo Jeong, Jae Hong Lee, Young Woong Suh

Research output: Contribution to journalArticle

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Abstract

To decompose dimethylhexane-1,6-dicarbamate (HDC) to hexamethylene diisocyanate (HDI), mixed CuO and ZnO catalysts with Cu/(Cu + Zn) ratio of 4 and 8% were prepared by coprecipitation (CP), sequential precipitation (SP) and incipient wetness impregnation (IW). The SP-derived CuO/ZnO catalysts showed higher HDC yields than those derived by CP and IW. The IW method produced CuO/ZnO catalysts consisting of larger CuO and ZnO particles compared to the two precipitation methods. The CP method led to substitution of Zn2+ by Cu2+ in the hydrozincite precursor phase, resulting in higher BET and Cu surface areas of CuO–ZnO catalysts due to intimate intergrowth of nano-sized particles. However, the inherent character of ZnO in the CP-derived catalysts was modified by interfacial contact between CuO and ZnO identified by UV–visible and Raman spectra. In contrast, the properties of CuO and ZnO, as well as the relatively large surface areas, were kept in the SP-derived catalysts owing to deposition of Cu precipitates to fully aged Zn precipitates. This is believed to be a benefit of the SP method for the reaction. Therefore, our preparation approach has great potential to be extended to various mixed oxide catalysts.

Original languageEnglish
Pages (from-to)3787-3796
Number of pages10
JournalResearch on Chemical Intermediates
Volume44
Issue number6
DOIs
Publication statusPublished - 2018 Jun 1

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Keywords

  • Carbamate decomposition
  • Coprecipitation
  • CuO/ZnO
  • Sequential precipitation

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