Abstract: The provided is a process for separating by absorption the pyrolysis gas from preparation of lower carbon olefins, wherein a primary absorbent and a secondary absorbent are introduced into the demethanizer to separate by absorption the feedstock of the demethanizer through countercurrent contact therewith at a moderate temperature and pressure, thereby to obtain a top fraction primarily comprising hydrogen and methane and a bottom fraction primarily comprising the absorbents and C2+ fraction, wherein the primary absorbent essentially is a mixed Cn or Cn+ fraction, the secondary absorbent essentially is a Cn? alkane fraction or mixed Cn? or Cn?+ fraction, and wherein n and n? are independently 3, 4 or 5 with the proviso when the secondary absorbent is a mixed fraction, n? is not 3.

Abstract: The present invention provides a method for preparing the polymer grade low-carbon olefin through separation of the methanol pyrolysis gas, including steps of the compression, impurity removal, and absorption and separation. In the absorption and separation step, the pyrolysis gas is sent to the front-end ethylene removing column, and then is, with the C4 absorbent, further absorbed and separated to produce polymer grade ethylene products, polymer grade propylene products, and C4 and C5 products. The moderate-temperature and moderate-pressure separation without a cold box according to the present invention provides safer production process, less investment in the equipment, as well as easier separation and lower energy consumption as a result of the front-end ethylene removing and C4 absorption and separation process.

Abstract: The provided is a process for separating by absorption the pyrolysis gas from preparation of lower carbon olefins, wherein a primary absorbent and a secondary absorbent are introduced into the demethanizer to separate by absorption the feedstock of the demethanizer through countercurrent contact therewith at a moderate temperature and pressure, thereby to obtain a top fraction primarily comprising hydrogen and methane and a bottom fraction primarily comprising the absorbents and C2+ fraction, wherein the primary absorbent essentially is a mixed Cn or Cn+ fraction, the secondary absorbent essentially is a Cn? alkane fraction or mixed Cn? or Cn?+ fraction, and wherein n and n? are independently 3, 4 or 5 with the proviso when the secondary absorbent is a mixed fraction, n? is not 3.

Abstract: The present invention provides a method for preparing the polymer grade low-carbon olefin through separation of the methanol pyrolysis gas, including steps of the compression, impurity removal, and absorption and separation. In the absorption and separation step, the pyrolysis gas is sent to the front-end ethylene removing column, and then is, with the C4 absorbent, further absorbed and separated to produce polymer grade ethylene products, polymer grade propylene products, and C4 and C5 products. The moderate-temperature and moderate-pressure separation without a cold box according to the present invention provides safer production process, less investment in the equipment, as well as easier separation and lower energy consumption as a result of the front-end ethylene removing and C4 absorption and separation process.