A process for the preparation of cysteine from cystine

Patent · Sat Dec 31 23:00:00 EST 1988

OSTI ID:866988

Chang, Shih-Ger ^[1]; Liu, David K ^[2]; Griffiths, Elizabeth A ^[3]; Littlejohn, David ^[2]

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1. El Cerrito, CA
2. Oakland, CA
3. Morristown, NJ

The present invention in one aspect relates to a process for the simultaneous removal of NO.sub.x and SO.sub.2 from a fluid stream comprising mixtures thereof and in another aspect relates to the separation, use and/or regeneration of various chemicals contaminated or spent in the process and which includes the steps of: (A) contacting the fluid stream at a temperature of between about 105.degree. and 180.degree. C. with a liquid aqueous slurry or solution comprising an effective amount of an iron chelate of an amino acid moiety having at least one --SH group; (B) separating the fluid stream from the particulates formed in step (A) comprising the chelate of the amino acid moiety and fly ash; (C) washing and separating the particulates of step (B) with an aqeous solution having a pH value of between about 5 to 8; (D) subsequently washing and separating the particulates of step (C) with a strongly acidic aqueous solution having a pH value of between about 1 to 3; (E) washing and separating the particulates of step (D) with an basic aqueous solution having a pH value of between about 9 to 12; (F) optionally adding additional amino acid moiety, iron (II) and alkali to the aqueous liquid from step (D) to produce an aqueous solution or slurry similar to that in step (A) having a pH value of between about 4 to 12; and (G) recycling the aqueous slurry of step (F) to the contacting zone of step (A). Steps (D) and (E) can be carried out in the reverse sequence, however the preferred order is (D) and then (E). In a preferred embodiment the present invention provides an improved process for the preparation (regeneration) of cysteine from cystine, which includes reacting an aqueous solution of cystine at a pH of between about 9 to 13 with a reducing agent selected from hydrogen sulfide or alkali metal sulfides, sulfur dioxide, an alkali metal sulfite or mixtures thereof for a time and at a temperature effective to cleave and reduce the cystine to cysteine with subsequent recovery of the cysteine. In another preferred embodiment the present invention provides a process for the removal of NO.sub.x, SO.sub.2 and particulates from a fluid stream which includes the steps of (A) injecting into a reaction zone an aqueous solution itself comprising (i) an amino acid moiety selected from those described above; (ii) iron (II) ion; and (iii) an alkali, wherein the aqueous solution has a pH of between about 4 and 11; followed by solids separation and washing as is described in steps (B), (C), (D) and (E) above. The overall process is useful to reduce acid rain components from combustion gas sources.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
• DOE Contract Number: AC03-76SF00098
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4837361
• OSTI ID: 866988
• Country of Publication: United States
• Language: English

Related Subjects

--sh
/999/423/435/
105
11
12
13
180
acid
acid moiety
acidic
acidic aqueous
adding
additional
agent
agent selected
alkali
alkali metal
amino
amino acid
amount
aqeous
aqueous
aqueous liquid
aqueous slurry
aqueous solution
ash
aspect
aspect relates
basic
carried
chelate
chemicals
cleave
combustion
combustion gas
components
comprising
comprising mixtures
contacting
contacting zone
contaminated
cysteine
cystine
degree
described
dioxide
effective
effective amount
embodiment
fluid
fluid stream
fly
fly ash
followed
formed
gas
gas source
hydrogen
hydrogen sulfide
ii
iii
improved
improved process
injecting
iron
iron chelate
liquid
liquid aqueous
metal
metal sulfide
metal sulfides
mixtures
moiety
moiety selected
optionally
optionally adding
overall
overall process
particulates
ph
ph value
preferred
preferred embodiment
preparation
process
produce
provides
rain
reacting
reaction
reaction zone
recovery
recycling
reduce
reducing
reducing agent
regeneration
relates
removal
reverse
selected
separating
separation
sequence
similar
simultaneous
simultaneous removal
slurry
solids
solids separation
solution
solution comprising
sources
spent
step
steps
stream
stream comprising
strongly
strongly acidic
subsequent
subsequently
sulfide
sulfides
sulfite
sulfur
sulfur dioxide
temperature
temperature effective
time
useful
value
various
various chemical
washing
zone