Research and Development of a Fluidized Bed Catalyst for Production of Phthalic Anhydride and Commercialization Thereof. (Part 2). Deactivation and Improvement of Silica-supported V2O5-K2O-SO3 Catalyst.

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  • ASAMI Yukio
    Chemical Div., Chiba Plant, Kawasaki Steel Corp. Gas Chemical Div., Iwatani Industrial Gases Corp.
  • IWASAKI Mamoru
    Chemical Div., Chiba Plant, Kawasaki Steel Corp.
  • AONO Toshinao
    Chemical Div., Chiba Plant, Kawasaki Steel Corp. Chemical Div., Mizushima Plant, Kawasaki Steel Corp.
  • HIROOKA Noboru
    Chemical Div., Chiba Plant, Kawasaki Steel Corp.
  • NOBUSAWA Tatsuya
    Technical Research Laboratories, Kawasaki Steel Corp.

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Other Title
  • 無水フタル酸製造用流動層触媒の開発と実用化　（第２報）　　シリカ担持Ｖ２Ｏ５‐Ｋ２Ｏ‐ＳＯ３触媒の活性劣化と改良
  • ムスイ フタルサン セイゾウヨウ リュウドウソウ ショクバイ ノ カイハツ ト ジツヨウカ ダイ2ホウ シリカ タンジ V2O5 K2O SO3 ショクバイ ノ カッセイ レッカ ト カイリョウ
  • Deactivation and Improvement of Silica-supported V<sub>2</sub>O<sub>5</sub>-K<sub>2</sub>O-SO<sub>3</sub> Catalyst
  • シリカ担持V<sub>2</sub>O<sub>5</sub>-K<sub>2</sub>O-SO<sub>3</sub>触媒の活性劣化と改良

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Abstract

Recently, a new spray-drying method was developed, using fine silica sols, which can easily prepare micro-spherical catalysts with uniform quality and good attrition. Use of the newly developed catalyst for fluidized-bed oxidation of naphthalene in a commercial plant achieved ideal operation with effective catalyst performance at start-up, so the yield of phthalic anhydride was about 4% higher than when using the catalyst licensed by Badger Corp. However, a rapid decrease in activity and poor fluidization of the catalyst occurred during naphthalene oxidation at lower temperature operation (320°C). The present study tried to clarify the cause of deactivation and poor fluidization of this eutectic catalyst, by investigating the change in catalyst active components using SEM-EPMA techniques and the melting point of eutectic mixtures. The changes in the catalyst were a result of the migration of active components and the change in the V2O5/K2O/SO3 molar ratio in the catalyst particles, caused by both the lower temperature operation and the load of naphthalene (W/F), forming a high melting point eutectic mixture at the catalyst surface. The volatality of SO2 from the catalyst surface may be involved in the decreased activity and poor fluidization. Evaluation tests at a commercial plant, using a new eutectic mixtures catalyst with a lower melting point modified by the addition of Cs2SO4, revealed high catalyst performance and stable operation. There was a good conelation between V5+ in the catalyst and the yield of phthalic anhydride at this plant, demonstrating that the presence of V5+ catalyzes the product formation.

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