Rabigh Refining & Petrochemical Co., a 50:50 joint venture of Saudi Arabian Oil Co. (Dhahran, both Saudi Arabia) and Sumitomo Chemical Co. Ltd. (Tokyo, Japan), is constructing a new plant to produce 200,000 m.t./yr of propylene oxide (PO). When the plant starts up next year, it will be the second commercial plant to use a byproductfree process developed by Sumitomo Chemical, the first being a 150,000-m.t./yr plant at the Chiba, Japan, factory, which was expanded to 200,000 m.t./yr in 2005. Conventional routes to PO either generate large volumes of: wastewater (the chlorohydrin process), styrene monomer (the Halcon process) or tert-butyl alcohol (the isobutene-oxidation process). In contrast, water is the only byproduct generated from Sumitomo’s PO process.
According to published patents and reports, Sumitomo’s PO process is based on a cumene feedstock. In the process (diagram), cumene is first oxidized in air (without a catalyst) at 90–130°C and 1–10 bar, into cumene hydroperoxide (CMHP) with a selectivity of over 95%. Propylene is then epoxylated with CMHP in a fixed-bed reactor over the company’s proprietary titaniumsilica
catalyst at 25–200°C and 1–100 bar, into PO (selectivity over 95%) and alphadimethylbenzyl
alcohol (CMA). CMA is hydrogenated into cumene which, together with unreacted cumene, is recycled into the process.
According to published patents and reports, Sumitomo’s PO process is based on a cumene feedstock. In the process (diagram), cumene is first oxidized in air (without a catalyst) at 90–130°C and 1–10 bar, into cumene hydroperoxide (CMHP) with a selectivity of over 95%. Propylene is then epoxylated with CMHP in a fixed-bed reactor over the company’s proprietary titaniumsilica
catalyst at 25–200°C and 1–100 bar, into PO (selectivity over 95%) and alphadimethylbenzyl
alcohol (CMA). CMA is hydrogenated into cumene which, together with unreacted cumene, is recycled into the process.
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