Pyrolysis gas treatment including halogen and/or sulfur removal
AssigneeEastman Chemical Company
InventorsDavid Eugene Slivensky, Daryl Bitting, Michael Gary Polasek, Xianchun Wu
Life of this patent
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Abstract
Processes and facilities for recovering and purifying a pyrolysis gas formed by pyrolyzing waste plastic are provided. One or more treatment processes may be used to treat the pyrolysis gas for use in one or more downstream chemical recycling processes. which can be used in forming a variety of recycled content products. The treatment processes may include a halogen removal system and/or a sulfur removal system.
Claims18
A process for purifying pyrolysis gas (pygas), the process comprising:
- (a) pyrolyzing a waste plastic to produce a pygas stream having a quantity of carbon dioxide (CO2) and a quantity of sulfur and/or sulfur-containing compounds;
- (b) treating the pygas stream to remove at least a portion of the quantity of CO2 and to thereby provide a CO2-depleted pygas stream;
- and
- (c) treating the CO2-depleted pygas stream to remove at least a portion of the quantity of sulfur and/or sulfur-containing compounds and to thereby provide a sulfur-depleted purified pygas stream.
A process for purifying pyrolysis gas (pygas), the process comprising:
- (a) pyrolyzing a waste plastic to produce a pygas stream comprising:
- (i) at least 1 ppm of hydrogen sulfide (H2S),
- (ii) at least 25 ppb of arsine,
- (iii) at least 25 ppb of phosphine, and/or
- (iv) at least 1 ppm carbonyl sulfide (COS);
- (b) optionally, contacting the pygas stream with a first reactant material in the presence of a catalyst material to convert at least a portion of the COS into hydrogen sulfide (H2S);
- (c) contacting the pygas stream with a second reactant material comprising one or more metal-oxide compounds to thereby:
- (i) convert at least a portion of the H2S into water and a metal-sulfide;
- (ii) convert at least a portion of the arsine into water and a metal-arsenide;
- (iii) convert at least a portion of the phosphine into water and a metal-phosphide;
- and/or
- (iv) convert at least a portion of the COS into carbon dioxide (CO2) and a metal-sulfide;
- and
- (d) removing at least a portion of the metal-sulfide, the metal-arsenide, and/or the metal-phosphide from the pygas stream to thereby form a purified pygas stream.
A process for purifying pyrolysis gas (pygas), the process comprising:
- (a) pyrolyzing a waste plastic to produce a pygas stream having a quantity of carbon dioxide (CO2) and a quantity of halogens;
- (b) treating the pygas stream in an absorber-stripper system to remove at least a portion of the quantity of CO2 and to thereby provide a CO2-depleted pygas stream;
- and
- (c) treating the CO2-depleted pygas stream to remove at least a portion of the quantity of halogens and to thereby provide a halogen-depleted purified pygas stream.
18-20. (canceled)
Dependencies are inferred from the claim text.