Depolymerization of lignin into high-value products

Lignin is the most abundant natural aromatic polymer source on the earth; the lignin structure contains three primary monolignols p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol. These units make the lignin structure a suitable raw material to obtain different value-added products, which has attracted the scientific community's attention. However, most lignin produced globally is still used as boiler fuel in carbohydrate processing plants, but lignin has shown innumerable times that due to its low value and high volume it has great potential to produce high value new products. If it is transformed into chemical compounds, its revenue can generate a multibillion-dollar lignin-based bioproducts industry. Numerous approaches have been reported for lignin fragmentation as an alternative way to produce chemicals currently extracted from fossil fuel sources. This review summarizes some of the most common methods to convert lignin into valuable products.