High Yttria–Zirconia and Yttria Ceramics for Petrochemical Reverse‐Flow Reactor Applications. (24th January 2014)

• Record Type: Journal Article
• Authors: Chun, ChangMin; Desai, Sanket; Hershkowitz, Frank; Ramanarayanan, Trikur A.
• Is Part Of: International journal of applied ceramic technology. Volume 12:(2015)Supplement 3
• Page Start: 585
• Page End: 597
• Publication Date: 2014-01-24
• Subjects: Ceramics -- Periodicals; Ceramics -- Technological innovations -- Periodicals; 620.1405
• DOI: 10.1111/ijac.12211
• Languages: English
• ISSNs: 1546-542X

Abstract

Abstract : Reverse‐flow reactors achieve the desired hydropyrolysis reaction of natural gas and other hydrocarbon feeds at very high temperatures of up to 2000°C, which enables the production of many high‐value chemicals. To identify refractory ceramic materials suitable for constructing key components of the reactor, the full range of solid solutions between zirconia and yttria having 18 to 100 mol% yttria have been tested in a laboratory reactor. Conventional yttria‐stabilized zirconia (YSZ) materials having 8 mol% Y2 O3 appear to accommodate reactor thermal severity, but are prone to a new form of corrosion termed ceramic dusting that is observed when pyrolysis and oxidation cycles are alternated under reverse‐flow conditions. Yttria and high yttria–zirconia ceramics having ~80 mol% or more yttria suppress ceramic dusting corrosion in steam‐free pyrolysis environments. The addition of low levels of steam of ~5% to the pyrolysis gas stream increases the stability of YSZ materials substantially, so that the stability threshold is closer to 40 mol% Y2 O3 in the yttria–zirconia system. The two approaches can be combined to optimize reactor performance. Key experimental results are presented and discussed taking into account the thermodynamic phase stability of the different phases.