Before the discovery of cellulolytic enzymes, processes that could thermochemically hydrolyze lignocellulosose to produce soluble sugars were studied and developed with some commercial use during wartime periods.
-Most of these processes were operated under fairly severe conditions and typically utilized concentrated acids at relatively low temperatures (200°C).
-Such harsh conditions generally resulted in relatively low recoverable sugar yields due to sugar degradation reactions that produced primarily aldehydes and organic acids, along with other undesirable compounds.
-Advances have been made in thermochemical acid hydrolysis processes to improve their commercialization potential in some niche opportunities, especially for concentrated acid processes.