Separation method for removing styrene from ethylbenzene-dehydrogenation tail gas and recovering hydrogen

Abstract

The invention relates to a separation method for removing small amount of styrene from ethylbenzene-dehydrogenation tail gas and recovering hydrogen and belongs to the field of petrochemical industry. The separation method comprises the following steps: adopting a dehydrogenizing material (ethylbenzene) as an absorbent, carrying out circular absorption on tail gas to reduce the content of the styrene to 30-50ppm; and recovering the ethylbenzene by compression and condensation to reduce the content of the styrene to 5-10ppm and meet the requirement for safe and stable operation of the hydrogen separation and purification section. After deep removal of the styrene, three different separation schemes are adopted for purifying hydrogen so as to meet different requirements of hydrogen purity and recovery rate; by variable-pressure absorption for purification, the concentration of hydrogen is more than 98%, the recovery rate is 80-85%, and the power consumption is 0.21kWh / Nm<3>; by hydrogen-membrane separation for purification, the concentration is more than 95%, the recovery rate is 90-95% and the power consumption is 0.7kWh / Nm<3>; and by coupling of variable-pressure absorption and hydrogen-membrane separation for purification, the concentration of the hydrogen is more than 98%, the recovery rate is 94-97%, simultaneously high purity and high yield are realized and the power consumption is 0.25kWh / Nm<3>.

Description

Technical field [0001] The invention relates to a method for removing styrene from ethylbenzene dehydrogenation tail gas and recovering hydrogen, and belongs to the field of petrochemical industry. Background technique [0002] Styrene is widely used in the production of synthetic materials such as styrene-butadiene rubber, polystyrene, ABS engineering plastics, SAN engineering plastics, SBS rubber, and the synthesis of fine chemical products such as drugs and dyes. It is a very important chemical intermediate. In 2006, the global production capacity of styrene reached 29.954 million tons, which was mainly produced through two processes: ethylbenzene catalytic dehydrogenation and ethylbenzene / propylene combined oxidation. In 2009, my country's styrene production capacity was approximately 4.869 million tons. Except for a few installations such as CNOOC-Shell Chemical Company, which adopted the combined ethylbenzene / propylene oxidation process, most of them were produced by ethylb...

AI Technical Summary

Problems solved by technology

The viscous oligomers formed after styrene self-polymerization will seriously affect the lubrication of the rotating parts in the compressor, which is not conducive to safe production

In addition, styrene self-polymerization also has a serious impact on the performance and service life of hydrogen separation equipment

In the pressure swing adsorption device, styrene cannot be desorbed from the adsorbent after self-polymerization, which is not conducive to the regeneration of the adsorbent, and affects the separation performance and the life of the adsorbent; in the hydrogen membrane separation equipment, styrene is attached to the membrane after self-polymerization. surface, reduce the gas permeation rate and affect the separation effect

Due to the possibility of spontaneous polymerization of a small amount of styrene in the tail gas of ethylbenzene dehydrogenation, there are potential safety hazards and the difficulty of stable operation of separation equipment. At present, there is no suitable method for long-term safe and stable treatment of tail gas of ethylbenzene dehydrogenation, separation and purification of hydrogen

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