Kinetics of Alkaline Thermochemical Degradation of Polysaccharides to Organic Acids

Very l i t t l e research has been done t o e x p l o r e commercial a p p l i c a t i o n o f t h e thermochemical d e g r a d a t i o n o f po l ysacchar ide m a t e r i a l s t o o r g a n i c a c i d s i n a l k a l i n e s o l u t i o n . Much o f t h e work on a l k a l i n e degrada t ion o f po l ysacchar ides has been conducted a t 100°C or l ower t o i n v e s t i g a t e mechanisms o f deg rada t ion , r e a c t i o n t e r m i n a t i o n and t h e e f f e c t s o f m o l e c u l a r s t r u c t u r e (1-4). However, l i t t l e conve rs ion o f po l ysacchar ides t o a c i d s occurs a t these low temperatures. Most i n v e s t i g a t i o n s a t h i g h e r temperatures have i n v o l v e d s tudy o f t h e a l k a l i n e p u l p i n g process a t app rox ima te l y 170OC (5 .6) . where po lysacchar ide d e g r a d a t i o n i s l i m i t e d and n o t d e s i r e d . Chesley e t a l . ( 7 ) proposed a commercial method f o r p roduc ing f o r m i c , a c e t i c , g l y c o l i c and l a c t i c a c i d s f rom c e l l u l o s i c m a t e r i a l s . However, optimum process parameters were n o t c l e a r , k i n e t i c d a t a was n o t ob ta ined , a d d i t i o n a l a c i d s were n o t i d e n t i f i e d , and most o f t h e s t a r t i n g p o l y s a c c h a r i d e m a t e r i a l was n o t accounted f o r . More recen t work has p r o v i d e d a d d i t i o n a l i n f o r m a t i o n on t h e thermochemical deg rada t ion o f c e l l u l o s e t o o r g a n i c a c i d s a t r e a c t i o n c o n d i t i o n s o f p r a c t i c a l i n t e r e s t ( 8 . 9 ) . However, no a d d i t i o n a l o r g a n i c a c i d s were i d e n t i f i e d , and the a c i d p r o d u c t i o n d a t a was d i f f i c u i t io i n t e r p r e t because o f i o n g heat-up t imes. No d a t a has been r e p o r t e d f o r t h e i m p o r t a n t po l ysacchar ide , s t a r c h , a t r e a c t i o n c o n d i t i o n s o f p r a c t i c a l i n t e r e s t .