| C4 fraction is a byproduct of the preparation of ethylene by steam pyrolysis and catalytic cracking. In 2005, although the output of ethylene was 7.555 million tons in china, the total amount of utilized C4 was 3.30 million tons. One of the key problems about the comprehensive development and utilization of C4 hydrocarbon is the separation of isobutene from C4 fraction.With C4 hydrocarbon from steam pyrolysis as materials, a refluence hydration process was developed based on the preparation technologies of tert-butyl alcohol from parallel current hydration of isobutene catalyzed by large particle columned (Ф5×5mm) cation exchange resin which showed some advantages, such as high throughput and small resistance.The results of the investigation of the refluence hydration showed that the hydration conversion of isobutene could reach 82.35% at 85 oC under the reaction pressure of 2.0 MPa with water and oil molar ratio of 5:1 and C4 hydrocarbon flow speed of 0.45~0.5mm/s. However, using the same catalyst as for the hydration, the results of the preparation of isobutene from tert-butyl alcohol dehydration showed that the conversion of tert-butyl alcohol was 80% with isobutene selectivity of 99% and purity of 99.9% at 90 oC under the pressure of 0.35 MPa.The technical and economic evaluation of 2000 t/a isobutene production installation revealed that the needed construction capital would be 4.8989 million Yuan (containing 445,000 Yuan of current capital) with building period of 1 year and investment callback period of 1.5 year.Based on the results of experimental investigation withФ100×10000 mm reactor in the laboratory, Lanzhou Petrochemical Research Institute finished"The Fundamental Design of 2000 t/a Isobutene Separation Installation from C4 Fraction". This installation was put into production in 2004. The running displayed that the conversion of isobutene was 75.26%, which gained its ends of the separation of isobutene from C4 hydrocarbon and possessed good industrial perspectives. |
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