(Daily Question) Coal-to-oil and olefins forum, 2018.1.23

Greene oil is an oligomer that forms in all C2, C3, and C4 hydrogenation reactors in ethylene plants and other petrochemical production facilities. Lüyóu is a mixture of C4–C20 unsaturated reactive components containing about 90% aliphatic dienes and 10% olefins and alkanes. In the C2 acetylene hydrogenation reactor (where acetylene is hydrogenated to produce ethylene and ethane), the most commonly used catalyst is palladium (Pd) supported on an alumina (AL2O3) carrier. Green oil polymers are formed as a side reaction of the hydrogenation process itself, and they cannot be completely avoided. The formation of this polymer begins with the dimerization of acetylene and hydrogen to yield butadiene, followed by the successive addition of acetylene molecules to form a backbone molecule that adsorbs on the Pd surface. The low relative molecular mass fraction of this green oil evaporates to form a gas stream, while some of the heavier fractions deposit in the pores of the catalyst. The remaining heavy fractions are carried away with the gas as fine droplets, most of which are less than 5 microns in size; therefore, the concentration of green oil in the gas ranges from approximately 100 ppmv to 1000 ppmv, depending on factors such as operating temperature, catalyst lifespan, CO content, and the H2/acetylene ratio. The gas leaving the hydrogenation reactor is cooled, and more green oil condenses into fine droplets, which deposit in the downstream heat exchangers, at the bottom of the dehydrator, as well as inside the C3 hydrogenation reactor bed and on the inner surfaces of the ethylene/propylene distillation column. These deposited fine droplets are composed of polymers and cause scaling in the equipment, which can lead to costly unplanned shutdowns to remove these accumulated sludge. The fuel gas used for desiccant regeneration removes the green oil deposited on the molecular sieve ； The fuel gas is thus contaminated by green oil. Then this contaminated fuel gas may cause scaling in the furnace’s low-NOx burners, leading to lower furnace efficiency and more frequent and costly cleaning of the burner nozzles. Various industrial methods for separating green oil from the exhaust gas stream of hydrogenation reactors include: washing the wet gas stream coming from the reactor with a liquid ethylene stream in a stripping tower, separating the wet gas through impaction against a packing bed, separating it using a mesh pad in a gas-liquid separator, and employing an efficient gas-liquid coalescing filter with specially formulated and designed filter media – the Pall Liquid/Gas Coalescing Filter.

Answer: Green oil is a polymer of lower-grade olefins, generally a by-product of acetylene hydrogenation; it has a high viscosity, and a green oil tower must be installed for hydrogenation deacetylation in order to remove it. The hydrogenation process can be alleviated by increasing the hydrogen-to-oil ratio, but the most fundamental solution is to develop catalysts with high selectivity for hydrogenation and dehydrogenation in order to reduce olefin polymerization.

Green oil is an oligomer formed in the carbon dioxide, carbon three, and carbon four reactors used in ethylene plants and other petrochemical production facilities. Lüyóu is a mixture of carbon four to carbon twenty unsaturated hydrocarbon reactants, containing 90% aliphatic dienes and 10% olefins and alkanes.

(DMTO) How is green oil generated in the olefin separation unit? Answer: During the acetylene hydrogenation reaction, a small portion of acetylene is converted into mixed polymers (green oil). To prevent freezing blockages, this substance must be completely removed from the feed to the ethylene distillation column. The outlet material from the hydrogenation reactor is mixed with the ethylene/ethane from the side stream of the ethylene distillation tower before entering the green oil buffer tank, where they come into full contact to remove the green oil.

Greene oil is an oligomer that forms in all C2, C3, and C4 hydrogenation reactors in ethylene plants and other petrochemical production facilities. Lüyóu is a mixture of C4–C20 unsaturated reactive components containing about 90% aliphatic dienes and 10% olefins and alkanes. In the C2 acetylene hydrogenation reactor (where acetylene is hydrogenated to produce ethylene and ethane), the most commonly used catalyst is palladium (Pd) supported on an alumina (Al2O3) carrier. Green polymer is formed as a by-product of the hydrogenation reaction itself.

This post was last edited by tczxs on 2018-1-24 08:47. Answer: During the acetylene hydrogenation reaction, a small portion of acetylene is converted into mixed polymers (green oil). To prevent freezing blockages, this substance must be completely removed from the feed to the ethylene distillation column. The outlet material from the hydrogenation reactor is mixed with the ethylene/ethane from the side stream of the ethylene distillation tower before entering the green oil buffer tank, where they come into full contact to remove the green oil.

In the acetylene hydrogenation reaction, under the action of a hydrogenation catalyst, acetylene undergoes polymerization to produce a polymer known as green oil.

The green oil formed in the acetylene hydrogenation reactor

Green oil is an oligomer formed in the carbon dioxide, carbon three, and carbon four reactors used in ethylene plants and other petrochemical production facilities. Lüyóu is a mixture of carbon four to carbon twenty unsaturated hydrocarbon reactants, containing 90% aliphatic dienes and 10% olefins and alkanes. The boiling point range of this green oil is 120~400°C. Green oil polymers arise as a side reaction of acetylene being hydrogenated by a palladium catalyst to produce ethylene and ethane, and they are impossible to completely avoid. The formation of this polymer begins with the dimerization of acetylene and hydrogen to yield butadiene, followed by continuous addition of acetylene and oligomerization to produce a backbone molecule that adsorbs on the Pd surface.

During the acetylene hydrogenation reaction, a small portion of acetylene is converted into mixed polymers (green oil). To prevent freezing blockages, this substance must be completely removed from the feed to the ethylene distillation column. The outlet material from the hydrogenation reactor is mixed with ethylene/ethane from the side stream of the ethylene distillation tower before entering the green oil buffer tank, where they come into full contact to remove the green oil