Methods for the production of para-xylene include flowing a xylenes-containing stream comprising PX, meta-xylene (MX), and ortho-xylene (OX), to a first crystallization stage. In addition, the methods include lowering a temperature of the xylenes-containing stream to below the eutectic point of the xylenes-containing stream within the first crystallization stage to crystallize at least some of the PX and at least some of one of both of the MX and the OX within the xylenes-containing stream. Further, the methods include separating the xylenes-containing stream into a first crystallization effluent stream and a first filtrate stream.

A method and an apparatus for preparing an oligomer, the method including supplying a feed stream including a monomer to a reactor to perform an oligomerization reaction, recovering unreacted monomer, and dissolving the recovered unreacted monomer in a solvent in a monomer dissolution device and supplying a discharge stream from the monomer dissolution device to the reactor. The method and the apparatus provide reduced investment costs and improved economic feasibility as there is no need to use a refrigerant at a very low temperature or install a separate compressor to recover and reuse the unreacted monomer in an oligomer production process.

A method and an apparatus for preparing an oligomer, the method including supplying a feed stream including a monomer to a reactor to perform an oligomerization reaction, recovering unreacted monomer, and dissolving the recovered unreacted monomer in a solvent in a monomer dissolution device and supplying a discharge stream from the monomer dissolution device to the reactor. The method and the apparatus provide reduced investment costs and improved economic feasibility as there is no need to use a refrigerant at a very low temperature or install a separate compressor to recover and reuse the unreacted monomer in an oligomer production process.

A method and an apparatus for preparing an oligomer, the method including supplying a feed stream including a monomer to a reactor to perform an oligomerization reaction, recovering unreacted monomer, and dissolving the recovered unreacted monomer in a solvent in a monomer dissolution device and supplying a discharge stream from the monomer dissolution device to the reactor. The method and the apparatus provide reduced investment costs and improved economic feasibility as there is no need to use a refrigerant at a very low temperature or install a separate compressor to recover and reuse the unreacted monomer in an oligomer production process.

A method for separating aromatic hydrocarbons by an extractive distillation, comprising introducing a hydrocarbon mixture containing aromatic hydrocarbons into the middle of an extractive distillation column (8); introducing an extraction solvent into the upper part of the extractive distillation column; after an extractive distillation, a raffinate containing benzene is discharged from the top of the column, wherein the benzene content is 3-40% by mass, and sent to the lower part of the extraction column (10); the extraction solvent is introduced to the upper part of the extraction column for a liquid-liquid extraction; a raffinate liquid free of aromatic hydrocarbons is discharged from the top of the extraction column; a rich solvent containing benzene is discharged from the bottom of the column and enters the upper-middle part of the extractive distillation column; the rich solvent obtained at the bottom of the extractive distillation column is sent to the solvent recovery column to separate the aromatic hydrocarbons and the solvent. By combining an extractive distillation with a liquid-liquid extraction ingeniously, the method can achieve the separation of aromatic hydrocarbons with a high purity and a high recovery rate, and a significant decrease of the energy consumption in the extraction and separation process.

A method for operating an acetylene hydrogenation unit of a steam cracking system that integrates a fluidized catalytic dehydrogenation (FCDh) effluent from a fluidized catalytic dehydrogenation (FCDh) system may include separating a cracked gas from the steam cracking system into at least a hydrogenation feed comprising at least acetylene, CO, and hydrogen, introducing the FCDh effluent to the separation system, combining the FCDh effluent with the cracked gas upstream of the separation system, or both. The method may include hydrogenating acetylene in the hydrogenation feed. Elevated CO concentration in the hydrogenation feed due to the FCDh effluent may reduce a reaction rate of acetylene hydrogenation. The acetylene hydrogenation unit may operate at an elevated temperature relative to normal operating temperatures when the portion of the FCDh effluent is not integrated, such that a concentration of acetylene in the hydrogenated effluent is less than a threshold acetylene concentration.

The present invention and embodiments thereof provide a process to separate ethylene products from impurities such as nitrogen, hydrogen, ethane, propane and isobutane without the need for distillation processes.

A method for separating a raw feed gas stream using a plurality of membrane module stages. The raw feed gas stream may be from a biogas process. Off-gas from another unit process in the system, such as a temperature swing adsorption unit or liquefaction unit, may be used as a low pressure sweep gas on the low pressure side of at least one of the membrane module stages. In one example, the sweep gas is used in a first membrane module stage. In another example, a stripping membrane module stage is provided and the sweep gas is used in the stripping membrane module stage. Optionally, portions of the off-gas could be directed to other streams in the system for the purpose of balancing compressor power requirements.

Process for the production of butenes and butadienes from waste plastics feedstocks comprising the steps in this order of: (a) providing a hydrocarbon stream A obtained by treatment of a waste plastics feedstock; (b) providing a hydrocarbon stream B; (c) supplying a feed C comprising a fraction of the hydrocarbon stream A and a fraction of the hydrocarbon stream B to a thermal cracker furnace comprising cracking coil(s); (d) performing a thermal cracking operation in the presence of steam to obtain a cracked hydrocarbon stream D; (e) supplying the cracked hydrocarbon stream D to one or more separation units; and (f) performing a separation operation to obtain different streams comprising isobutene, 1-butene, 2-butene, 1,2-butediene and 1,3-butadiene; wherein in step (d): • the coil outlet temperature is ≥ 800 and ≤ 850° C. and • the weight ratio of steam to feed C is > 0.3 and < 0.8.

Process for the production of butenes and butadienes from waste plastics feedstocks comprising the steps in this order of: (a) providing a hydrocarbon stream A obtained by treatment of a waste plastics feedstock; (b) providing a hydrocarbon stream B; (c) supplying a feed C comprising a fraction of the hydrocarbon stream A and a fraction of the hydrocarbon stream B to a thermal cracker furnace comprising cracking coil(s); (d) performing a thermal cracking operation in the presence of steam to obtain a cracked hydrocarbon stream D; (e) supplying the cracked hydrocarbon stream D to one or more separation units; and (f) performing a separation operation to obtain different streams comprising isobutene, 1-butene, 2-butene, 1,2-butediene and 1,3-butadiene; wherein in step (d): • the coil outlet temperature is ≥ 800 and ≤ 850° C. and • the weight ratio of steam to feed C is > 0.3 and < 0.8.