成果報告書詳細
管理番号20120000000518
タイトル平成23年度中間年報 グリーン・サステイナブルケミカルプロセス基盤技術開発 触媒を用いる革新的ナフサ分解プロセス基盤技術開発 高性能ゼオライト触媒を用いる革新的ナフサ分解プロセスの開発
公開日2012/9/1
報告書年度2011 - 2011
委託先名触媒技術研究組合/(独)産業技術総合研究所/国立大学法人東京工業大学/国立大学法人北海道大学/国立大学法人横浜国立大学
プロジェクト番号P09010
部署名環境部
和文要約和文要約等以下本編抜粋:
1.研究開発の内容および成果等
「高性能ゼオライト触媒を用いる革新的ナフサ分解プロセスの開発」では、既存熱分解プロセスに対して、石油化学品(エチレン、プロピレン、ブテン、BTX等)の収率、選択性を高めるために必要な高性能なゼオライト触媒等の開発を行うとともに、ナフサ分解プロセス内のエネルギーバランス、分離工程におけるエネルギー消費に関するプロセス設計、最適化を行って、早期に革新的な実用化プロセスに繋がる基盤技術を開発する。
平成23年度実施計画に基づき高性能ゼオライト触媒を用いる革新的ナフサ分解プロセスの開発における研究開発成果を以下に報告する。
英文要約We are continuing to develop high-performance zeolite catalysts that are able to produce useful petrochemical feedstocks such as ethylene, propylene, butenes and BTX from naphtha in higher yields and selectivity than the conventional thermal cracking processes. Through the screening done in the previous year, ZSM-5 proved to be the most promising catalyst in terms of activity, selectivity and duration. We have synthesized ZSM-5 samples with the Si/Al ratio changed. The tetrahedral 27Al peak in the NMR spectra shifted to upfield with increasing Al content. Simultaneously, the catalytic activity increased and the activation energy for the hexane cracking decreased, probably because of difference in the T sites in the MFI framework occupied by Al atoms depending on the Al content. By analyzing the selectivities for products, it was concluded that at 923 K the unimolecular cracking prevailed irrespective of the Al content.
Since deactivation of the catalysts is the critical problem to be addressed, we have adopted various methods in order to extend the catalyst duration. The addition of P and transition metals to ZSM-5 as well as its high-temperature pretreatment and acid pretreatment was helpful in improving the catalyst duration with the selectivity for the desired products maintained. Inactivation of acid sites on the external surface also favorably affected the life. These improvements are ascribed to the retardation of coke formation as a result of optimization of the number and location of acid sites. The nano-sized catalyst remained effective even after 90% of the external surface were covered by coke as revealed by rate analysis. The deactivation is also caused by dealumination of the catalyst. ZSM-5 samples synthesized in the absence of structure-directing agents were found to be inherently hard to dealuminate compared to the samples crystallized in the presence of tetrapropylammonium ions.
Techniques to form the catalysts were also explored. The type and the amount of forming agents and the conditions for milling, extrusion, and washing were optimized. Formed catalysts were tested in semi-bench scale reactors. The crushing strength of the catalyst 5 mm in diameter achieved 6.3 kg cm-2. However, it showed a lower initial activity than the powdery catalyst although the catalyst 3 mm in diameter was as active as the powdery one.
We are also developing fundamental technologies through process design and optimization with respect to energy balance in the naphtha cracking process and energy consumption in the separation/purification step. We have concluded that the fixed-bed process we are developing is superior to the preceding fluidized-bed process if the regeneration time is shortened to 8 hours while the activity is kept for 48 hours.
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