In this study, the simultaneous effect of microwave-ultrasound (MW + US) irradiations was compared with those of microwave (MW) and ultrasound (US) applied individually for the depolymerization of Kraft lignin in a hybrid microwave-ultrasound high pressure chemical reactor. The bio-oils obtained upon depolymerization were analyzed by GC–MS, CHNS, MALDI-TOF-MS, 2D-HSQC NMR, TGA and FTIR techniques. The highest bio-oil yield of 48.2% was obtained upon depolymerization of Kraft lignin with hybrid MW + US irradiations for 1 h under autogenous pressure while only 42.1% and 25.5% bio-oil yields were obtained for MW and US irradiations, respectively. MALDI-TOF MS spectra suggested the presence of significant amount of dimers in the bio-oil obtained over hybrid MW + US process than US and MW processes. The simultaneous effect of MW and US reduced the repolymerization of reaction intermediates thus favoring relatively low residue and high bio-oil yield. 2D-HSQC NMR demonstrated considerable degradation of the representative inter-unit linkages (β-O-4 and β-5). The HHV_Boie of the bio-oils obtained over US (29.28 MJ/Kg) and MW + US (29.21 MJ/Kg) irradiations were quite comparable. Although the thermal stability of the bio-oils followed the order MW > MW + US > US, the bio-oil obtained over hybrid MW + US was superior in both quality and quantity than obtained over MW and US irradiations.

在这项研究中，将微波-超声波（MW + US）照射的同时效果与微波（MW）和超声（US）分别用于牛皮纸木质素在混合微波-超声波高压化学反​​应器中解聚的效果进行了比较。解聚后获得的生物油通过GC-MS，CHNS，MALDI-TOF-MS，2D-HSQC NMR，TGA和FTIR技术进行了分析。在自生压力下，用杂合MW + US辐照对牛皮纸木质素解聚1 h，可获得最高的生物油收率48.2％，而MW和US辐照分别仅获得42.1％和25.5％的生物油收率。MALDI-TOF MS光谱表明，与美国和MW流程相比，通过MW + US混合流程获得的生物油中存在大量的二聚体。MW和US的同时作用减少了反应中间体的再聚合，因此有利于较低的残留物和较高的生物油产率。2D-HSQC NMR证实了代表性的单元间键（β-O-4和β-5）的降解。HHV_•伯伊在美国获得的生物油（29.28兆焦/千克）和MW +美国（29.21兆焦/千克）照射是相当具有可比性。尽管生物油的热稳定性遵循MW> MW + US> US的顺序，但是通过混合MW + US获得的生物油在质量和数量上均优于通过MW和US辐照获得的生物油。