Vanillin from lignosulfonates

In the past, processes for the production of vanillin from lignosulfonates and dimethyl sulfide and dimethyl sulfate were known, but these have been abandoned due to lower production costs with petrochemical raw materials [12]. 

The use of the lignin fraction is much more cumbersome currently the best-known chemical of a real commercial importance is vanillin, which is obtained by oxidation of the black liquor. Another example is a product called spray-dried lignosulfonate (as sodium salt) obtained from the older, acidic sulfite pulping process. It is sold as a commercial product primarily as a concrete additive for enhanced strength. Since the cement industry is one of the big contributors of carbon dioxide emissions (due to the production of calcium oxide from calcium carbonate), the use of this renewable, wood-derived product not only is fossil-carbon neutral in itself but also reduces carbon dioxide emission due to the diminished need for cement in large infrastructures made of concrete. 

Howard A process for separating lignosulfonates from sulfite liquor from papermaking. The lignosulfonates are precipitated as their calcium salts. The product is used in the manufacture of vanillin. 

The production of vanillin for flavoring pxurposes still provides a major useful outlet for softwood lignins, but the lignosulfonates from a few mills suffice to saturate the market, even though the yield of vanillin is low. 

A large amount of research has been done on developing products from the waste sulfite liquor, and some success has been achieved. Vanillin, alcohol, and torula yeast can be produced as by-products, and the lignosulfonates are used as viscosity modifiers in drilling muds and for similar purposes. However, the... 

The guaiacol process yields vanillin with consistent high quality and sufficient volume to meet demand. At present, this process is advantageous relative to alternate routes from waste lignosulfonates obtained from the pulp and paper industry and an ort/io-chloronitrobenzene (OCNB) process that has environmental concerns [33]. 

From a historical perspective, two other large-volume uses include production of vanillin and dimethyl sulfoxide (DMSO) (91). Commercially, softwood spent sulfite liquors or lignosulfonates can be oxidized in alkaline media by oxygen or air to produce vanillin [121-33-5]. 

Expanders for Lead-Acid Batteries. Oxylignin, a sodium lignosulfonate derived from the vanillin process, is the premier expander for lead-acid batteries (99). When added to the negative plate at dosages of 0.1-0.5%, battery lifetimes are expanded from days to years. 

There have been numerous efforts to make use of the huge volume of 1. that result from paper pulping. Only 2% of the 1. is separated. Most of the crude material is burned in the power stations of the paper mills. ->Lignosulfonate is the only large-volume derivative of 1. All other efforts to modify Kraft 1. (ozonization, carboxylation, condensation with formaldeyde) and attempts to make cationic 1. as emulsifiers for bitumen have led to only small applications. L. has also been used for commercial production of - vanillin. 

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