A method for preparing a purified styrene composition is provided. The method includes providing a crude composition and subjecting the crude composition to at least one crystallization step. The crude composition contains 70% by weight or more styrene based on the total weight of the crude composition. The at least one crystallization step comprises at least one of a static crystallization stage and a dynamic crystallization stage. The crude composition contains at least one impurity selected from the group consisting of: color inducing species, oxygenates, sulfur species, alpha-methylstyrene, and mixtures thereof.

The invention provides a process for the separation of MEG and 1,2-BDO from a first mixture comprising MEG and 1,2-BDO, said process comprising the steps of: (i) providing said first mixture comprising MEG and 1,2-BDO as a feed to a distillation column; (ii) providing a feed comprising glycerol to the distillation column above the first mixture; (iii) operating the distillation column at a temperature in the range of from 50 to 250° C. and a pressure in the range of from 0.1 to 400 kPa; (iv) removing a stream comprising MEG and glycerol as a bottoms stream from the distillation column; and (v) (v) removing a stream comprising 1,2-BDO above the point at which the feed comprising glycerol is provided to the distillation column.

The invention provides a process for the separation of MEG and 1,2-BDO from a first mixture comprising MEG and 1,2-BDO, said process comprising the steps of: (i) providing said first mixture comprising MEG and 1,2-BDO as a feed to a distillation column; (ii) providing a feed comprising glycerol to the distillation column above the first mixture; (iii) operating the distillation column at a temperature in the range of from 50 to 250° C. and a pressure in the range of from 0.1 to 400 kPa; (iv) removing a stream comprising MEG and glycerol as a bottoms stream from the distillation column; and (v) (v) removing a stream comprising 1,2-BDO above the point at which the feed comprising glycerol is provided to the distillation column.

A method of desalinating an aqueous composition includes forming a hetero-azeotrope mixture by combining the aqueous composition with an entrainer, the aqueous composition including at least one salt, and subjecting the hetero-azeotrope mixture to distillation at a distillation temperature of less than the boiling temperature of the aqueous composition for an operating distillation pressure, resulting in separating the hetero-azeotrope mixture into a distillation bottoms liquid and a multi-phase condensate. The method includes recovering the multi-phase condensate having an entrainer-rich phase and an aqueous phase, the aqueous phase comprising desalinated water, and removing a portion of the aqueous phase from the multi-phase condensate to recover the desalinated water. Systems for conducting the method of desalinating an aqueous stream are also disclosed.

A method of producing aromatic hydrocarbons including: supplying a raw material stream to a C6 separation column, supplying an upper discharge stream from the C6 separation column to a first gasoline hydrogenation unit, and supplying a lower discharge stream from the C6 separation column to a C7 separation column; supplying an upper discharge stream from the C7 separation column to the first gasoline hydrogenation unit and supplying a lower discharge stream from the C7 separation column to a C8 separation column; separating benzene and toluene from a discharge stream from the first gasoline hydrogenation unit; removing a lower discharge stream from the C8 separation column and supplying an upper discharge stream from the C8 separation column to a second extractive distillation column; and separating styrene from a lower discharge stream from the second extractive distillation column and separating xylene from an upper discharge stream from the second extractive distillation column.

A method of producing aromatic hydrocarbons including: supplying a raw material stream to a C6 separation column, supplying an upper discharge stream from the C6 separation column to a first gasoline hydrogenation unit, and supplying a lower discharge stream from the C6 separation column to a C7 separation column; supplying an upper discharge stream from the C7 separation column to the first gasoline hydrogenation unit and supplying a lower discharge stream from the C7 separation column to a C8 separation column; separating benzene and toluene from a discharge stream from the first gasoline hydrogenation unit; removing a lower discharge stream from the C8 separation column and supplying an upper discharge stream from the C8 separation column to a second extractive distillation column; and separating styrene from a lower discharge stream from the second extractive distillation column and separating xylene from an upper discharge stream from the second extractive distillation column.

A carbon dioxide extraction system which recirculates CO.sub.2 and/or other gases in a continuous loop for maximum extraction efficiency and which recovers substantially all gases at the end of the extraction cycle for cost savings and greater workplace safety. The extractor utilizes a dual pumping system which can incorporate high vapor pressure CO.sub.2 and/or lower vapor pressure gases such as propane, butane, chemical refrigerants such as R134a, and other lower vapor pressure gases. The system allows the operators to work with supercritical CO.sub.2 alone with high pressure liquid pump(s), lower vapor pressure gases alone with modified refrigerant recovery pump(s), or a mixture of CO.sub.2 and lower vapor pressure gases using a combination of high pressure liquid pump(s) for extraction and modified refrigerant recovery pump(s) for full recovery of gases at the end of an extraction cycle.

A carbon dioxide extraction system which recirculates CO.sub.2 and/or other gases in a continuous loop for maximum extraction efficiency and which recovers substantially all gases at the end of the extraction cycle for cost savings and greater workplace safety. The extractor utilizes a dual pumping system which can incorporate high vapor pressure CO.sub.2 and/or lower vapor pressure gases such as propane, butane, chemical refrigerants such as R134a, and other lower vapor pressure gases. The system allows the operators to work with supercritical CO.sub.2 alone with high pressure liquid pump(s), lower vapor pressure gases alone with modified refrigerant recovery pump(s), or a mixture of CO.sub.2 and lower vapor pressure gases using a combination of high pressure liquid pump(s) for extraction and modified refrigerant recovery pump(s) for full recovery of gases at the end of an extraction cycle.

A method for recovering base oil from waste lubricating oil by separating base oil range constituents from a waste lubricating oil mixture, thereafter separating higher quality base oil constituents and lower quality base oil constituents from the base oil recovered from the waste lubricating oil mixture and thereafter treating the lower quality base oil constituents to produce marketable base oil. The total base oil produced from a waste lubricating oil mixture by this process is greater than the quantity producible by previous processes using only base oil separation from the waste lubricating oil mixture or processes which use only treatment of the base oil recovered from the waste lubricating oil mixture to produce the product base oil.

A method for recovering base oil from waste lubricating oil by separating base oil range constituents from a waste lubricating oil mixture, thereafter separating higher quality base oil constituents and lower quality base oil constituents from the base oil recovered from the waste lubricating oil mixture and thereafter treating the lower quality base oil constituents to produce marketable base oil. The total base oil produced from a waste lubricating oil mixture by this process is greater than the quantity producible by previous processes using only base oil separation from the waste lubricating oil mixture or processes which use only treatment of the base oil recovered from the waste lubricating oil mixture to produce the product base oil.