16815
It involves ultrafiltration as a fractionation process to separate different molecular weight lignin fractions followed by a hydrogen - free , mild , hydrogenolytic , heterogeneously catalyzed methodology assisted by microwave irradiation to obtain simple phenolic , monomeric products by depolymerization using a nickel - based catalyst .
 Chemical: hydrogen; Chemical: phenolic
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: hydrogen; Chemical: phenolic