Energy efficient propylene production by catalytic cracking of light naphtha over zeolite based composites

Title : Energy efficient propylene production by catalytic cracking of light naphtha over zeolite based composites

Abstract:

Propylene as a basic chemical becomes significant in petrochemical industry because of its increasing global demand. However, it is difficult to meet the increasing demand by conventional thermal cracking of naphtha feed due to its low propylene selectivity. Additionally, thermal cracking processes, proceeding at higher temperatures than 800^oC, are unfavorable in terms of energy consumption and carbon dioxide emission. It is thus necessary to establish any alternative method for producing propylene efficiently from widely available feed (e.g., light-naphtha). Though catalytic cracking of light-naphtha fraction over zeolites in fixed-bed operation have been actively investigated as a promising choice for on-purpose propylene production, this method hasn’t been commercialized because stable catalysts, being applicable to fixed-bed reactor, are still undeveloped. In this work, unique composite catalysts, consisting of MFI-type zeolites and silicon oxide, have been developed on the basis of original concept to demonstrate efficient propylene production from light naphtha in fixed-bed operation. Excellent properties of proprietary catalysts are summarized below.
 

1. The Fe-Ga-Al-MFI zeolites, giving high propylene selectivity, combined with silicon oxide were employed as composite catalysts for cracking reaction. The zeolite-based catalysts exhibited the following excellent performance in light-naphtha cracking at moderate temperatures (< 650^oC) using bench-scale facilities: (A) Higher overall propylene yield than 30 wt% (propylene yield in thermal cracking: ca. 15 wt%); (B) Longer lifetime than 1,000 h without regeneration.
2. Energy consumption in catalytic reactor was remarkably reduced compared to conventional pyrolysis furnace, because catalytic cracking proceeded without steam at lower than 650^oC. As a consequence, total amounts of both naphtha feed, required for producing unit amounts of valuable products (ethylene, propylene, butenes and BTX), and carbon dioxide emitted in cracking process were estimated to be saved by ca. 15 wt%, respectively, compared to conventional thermal cracking.
   
   It was confirmed from these technological viewpoints that that catalytic cracking of light naphtha over the zeolite-based composites in fixed-bed operation has great potential as an efficient method for on-purpose propylene production.

Biography:

Shinya Hodoshima obtained a PhD from the Tokyo University of Science for a work on organic chemical hydrides for hydrogen storage and transportation in 2001. After he dedicated himself to investigating catalytic chemistry and energy chemistry at the Tokyo University of Science, he joined Chiyoda Corporation in 2006. He has investigated zeolite synthesis and catalytic processes using zeolites since 2010. His research interests include applied catalysis, chemical reaction engineering and hydrogen energy systems. He received the outstanding presentation award at the 79^th Spring Meeting of the Chemical Society of Japan (2001), the best paper award in the Fuels & Petrochemicals division at the AIChE Spring Meeting (2014) and the NEDO excellent research award from the New Energy and Industrial Technology Development Organization (2019).