Wood Derived Chemicals

Each year nearly 200 x 108 of wood are harvested from the nation’s forest approximately 30 x 106 t are discarded as tree tops, stumps, roots, or scrapped logs. Half of the harvested round wood is converted into lumber, poles and similar and similar wood products. The remainder is converted into pulp and paper. Wood processors classify wood into two groups:

1. Hardwoods, which come from deciduous trees, and
2. Softwoods, which come from conifers.

The actual hardness or softness of the wood is irrelevant. Wood is a splendid , renewable resource and very valuable, but waste is enormous. It has been suggested that biomass must be handled like other valuable product, everything must be sold except the sound of the tree falling. Many new products are technically, but not economically, feasible.

Underutilization of wood product arises from the complexity of the material, lack of integration of chemical, pulp and lumber companies disinterest of processing companies in producing and selling by-product, lack of chemical knowledge or interest, and the dilute from in which many of the by-products are valuable. Since environment laws have made the stream dumping of pulp mill waste products impossible, some real interest in waste use has developed, but most such envisioned uses are as fuel. As the price of petroleum products rises, sylvichemicals become more enticing, but the chemistry is more complex than that necessary for petroleum processing. The use of wood as a fuel seems undesirable for such a complex raw material.

The solid portion of wood is over 95% organic. It is a mixture of three groups of polymers.

1. Cellulose, which is approximately 45% of the dry weight in an ordered array of high molecular weight glucose polymer chains, currently most valuable as fiber.
2. Hemicellulose (20 to 25%) is a disordered array of several sugar polymers for which there is currently no economical use except as fuel.
3. Lignin (20 to 25%), which serves as binder for the cellulose fibers, is a complex amorphous polyphenol polymer. These extractive vary with the species and the location in the tree; they vary from 5 to 25% by weight and constitute several classes of chemicals.