SUNKAIER process has the process technology for the styrenics monomer, polymers and related catalyst covering:
EPS suspension polymerization
ABS continuous mass polymerization
State-of-the-art technology to produce high-purity ethylbenzene (EB) by liquid-phase alkylation of benzene with ethylene. The EB process uses specially formulated, proprietary zeolite catalyst from . The process can handle a range of ethylene feed compositions ranging from chemical grade (70% ethylene/30% ethane) to polymer grade (100%). Process description:
Benzene and ethylene are reacted over a proprietary zeolite catalyst in a fixed-bed, liquid-phase reactor. Fresh benzene is combined with recycle benzene and fed to the alkylation reactor (1). The combined benzene feed flows in series through the beds, while fresh ethylene feed is distributed between the beds. The reaction is highly exothermic, and heat is removed between the reaction stages by generating steam. Unreacted benzene is recovered from the overhead of the benzene column (3), and EB product is taken as overhead from the EB column (4). A small amount of polyethylbenzene (PEB) is recovered in the over head of the PEB column (5) and recycled back to the transalkylation reactor (2) where it is combined with benzene over a proprietary zeolite catalyst to produce additional EB product. A small amount of flux oil is recovered from the bottom of the PEB column (5) and is usually burned as fuel. The catalysts are non-corrosive and operate at mild conditions, allowing for all carbon-steel construction. The reactors can be designed for 2–5 year catalyst cycle length, and the catalyst is fully regenerable. The process does not produce any hazardous effluent.
Yields and product quality:
Both the alkylation and trans-alkylation reactions are highly selective, producing few byproducts. The EB product has a high purity (99.9 wt% minimum) and is suitable for styrene unit feed. Xylene make is less than 10 ppm. The process has an overall yield of more than 99.7%.
Economics: The EB process features consistently high product yields over the entire catalyst life cycle, high product purity, low energy consumption, low investment cost, and simple, reliable operation.
Typical raw material and utilities, per metric ton of EB
Ethylene, mtons 0.265
Benzene, mtons 0.738
To produce polymer-grade styrene monomer (SM) by dehydrogenating ethylbenzene (EB) .
In the SM process, EB is catalytically dehydrogenated to styrene in the presence of steam. The vapor phase reaction is carried out at high temperature and under vacuum. The EB (fresh and recycle) is combined with superheated steam, and the mixture is dehydrogenated in a multistage reactor system (1). A heater reheats the process gas between stages. Reactor effluents are cooled to recover waste heat and condense the hydrocarbons and steam. Uncondensed offgas containing mostly hydrogen is compressed and is used as fuel or recovered as a valuable byproduct. Condensed hydrocarbons from an oil/water separator (2) are sent to the distillation section. Process condensate is stripped to remove dissolved aromatics and then used internally for steam generation. A fractionation train (3,4) separates high-purity styrene product; unconverted EB, which is recycled; and the relatively minor byproduct tar, which is used as fuel. In additional columns (5,6), toluene is produced as a minor byproduct and benzene is normally recycled to the upstream EB process. Typical SM product purity ranges from 99.85% to 99.95%. The process provides high product yield due to a unique combination of catalyst and operating conditions used in the reactors and the use of a highly effective polymerization inhibitor in the fractionation columns. Specially designed reactors are used to achieve the oxidation and dehydrogenation reactions. In oxidative reheat, oxygen is introduced to selectively oxidize part of the hydrogen produced over a proprietary catalyst to reheat the process gas and to remove the equilibrium constraint for the dehydrogenation reaction. The process achieves up to about 75% EB conversion per pass, eliminates the costly interstage reheater, and reduces superheated steam requirements.