Page 11 - Microsoft Word - Methyl Ester Sulfonate Products 5th Cesio v19,R1.doc

PROCESS CONDITIONS

Sulfonation of methyl ester feedstocks in the pilot plant is performed in a falling film reactor
at a rate of about 0.1 kg-mole per hour. The reactor inlet SO 3 gas concentration is 7 mole %.
The reactor inlet gas temperature is about 42°C. The ME feedstock is supplied to the reactor
at a temperature ranging from 40°C to 56°C, well above the freeze point of the particular ME
feedstock. The reactants are mass flow controlled to maintain a fixed mole ratio of SO 3 to
ME (MR). For the six feedstocks the MR ranged from 1.2 to 1.3. The choice of MR is
dependent on the expected selectivity of the particular ME to side-reactions and byproduct
formation. These include oxidation of the alkyl chain by SO 3, sulfonation of some of the
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resulting olefin sites, formation of methyl sulfuric acid, and hydrolysis of the ester to form
di-salt. The MESA is transferred to the acid digester system where it rapidly reaches the
desired digestion temperature. After the MESA is digested the methanol (35 to 40 wt%,
digested MESA basis) and 50% hydrogen peroxide are ratio added with the MESA into the
MES bleacher. A significant amount of exothermic reaction occurs in the bleacher. The acid
bleaching step requires 1 to 1.5 hours. More bleaching time is better in terms of degree of
color reduction as long as not all of the available peroxide is consumed. The excess methanol
effectively limits the production of di-salt, and significantly reduces the viscosity of the
mixture, which improves mixing and heat transfer through the bleaching process. Bleached
MESA is forwarded to the neutralizer where a controlled proportion of 50% sodium
hydroxide is admixed with the bleached MESA and a large recycle stream of neutralized
paste. Neutralized MES paste continuously discharges to the stripper / dryer pilot plant,
where the excess water and methanol are removed. The dryer pilot plant functions as a
distinct processing system, and processes concentrated pastes at rates of about 60 kg/hr. For
the stripping process the MES inlet temperature is about 100°C and the separation vessel
operates under vacuum conditions at 200 Torr or greater. For the drying process the MES
inlet temperature is about 145°C and operates under vacuum conditions at 120 to 200 Torr.
No significant increase in di-salt occurs at the elevated process temperatures of the dryer, and
the product color is stable.

CONCLUSION

Production of high quality MES requires more sophisticated equipment than linear
alkylbenzene sulfonate or fatty alcohol sulfate but it has strong appeal because ME is an
inexpensive, natural and renewable feedstock. Methyl ester sulfonates provide superior
surfactant properties at low cost, and therefore a strong economic incentive to substitute MES
for traditional surfactants in many applications. Production capacity of MES will increase in
the next few years. More formulation work can be expected utilizing different types of ME
feedstock based on the concentrated and ultra-concentrated forms of MES. There will be
many new competitive products introduced into the marketplace.

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to be used only by the addressee to evaluate this proposal. Use, disclosure, distribution or duplication for any other purpose or to any person
or organization except the addressee without prior, written permission from The Chemithon Corporation is strictly prohibited.