The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is si...The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is significantly improved under microwave irradiation, reaching 15.77% under a relatively mild liquefaction condition of 10 wt% H2SO4 as the catalyst, 10 wt% phenol as the hydrogen-donor reagent at 120 ℃ for 40 rain. Compared with conventional thermal liquefaction process, microwave irradiation promotes the cleavage of C-C bonds, which gives an extra 29% of Caryl-Cα bond cleavage, and increases the yield of monophenolic compounds from 0.92% to 13.61% under the same conditions. The excessive temperature and prolonged time under microwave irradiation will promote the recondensation of degraded lignin fragments, so the key to obtain high yield of monophenolic compounds is to avoid the recondensation reaction. The selected solid catalyst promotes the dissociation of methoxy groups, and the addition of phenol into liquefaction can only slightly improve the yield of monophencolic compounds.展开更多
Manganese dioxide(MnO2)is a widely used and well-studied 3-dimensional(3D)transition metal oxide,which has advantages in ultrafast optics due to large specific surface area,narrow bandgap,multiple pores,superior elect...Manganese dioxide(MnO2)is a widely used and well-studied 3-dimensional(3D)transition metal oxide,which has advantages in ultrafast optics due to large specific surface area,narrow bandgap,multiple pores,superior electron transfer capability,and a wide range of light absorption.However,few studies have considered its excellent performance in ultrafast photonics.y-MnO2 photonics devices were fabricated based on a special dual-core,pair-hole fiber(DCPHF)carrier and applied in ultrafast optics fields for the first time.The results show that the soliton molecule with tunable temporal separation(1.84 to 2.7 ps)and 600-MHz harmonic solitons are achieved in the experiment.The result proves that this kind of photonics device has goodapplications in ultrafast lasers,high-performance sensors,fiber optical communications,etc.,which can help expand the prospect of combining 3D materials with novel fiber for ultrafast optics device technology.展开更多
基金supported by the National Basic Research Program of China(2012CB215302)Guangdong Provincial Natural Science Fund(9151064101000082)
文摘The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is significantly improved under microwave irradiation, reaching 15.77% under a relatively mild liquefaction condition of 10 wt% H2SO4 as the catalyst, 10 wt% phenol as the hydrogen-donor reagent at 120 ℃ for 40 rain. Compared with conventional thermal liquefaction process, microwave irradiation promotes the cleavage of C-C bonds, which gives an extra 29% of Caryl-Cα bond cleavage, and increases the yield of monophenolic compounds from 0.92% to 13.61% under the same conditions. The excessive temperature and prolonged time under microwave irradiation will promote the recondensation of degraded lignin fragments, so the key to obtain high yield of monophenolic compounds is to avoid the recondensation reaction. The selected solid catalyst promotes the dissociation of methoxy groups, and the addition of phenol into liquefaction can only slightly improve the yield of monophencolic compounds.
基金supported by the Starting Grants of Shaanxi Normal University(grant nos.1112010209 and 1110010717)Fundamental Research Funds for the Central Universities(no.GK202103013 and 2021CSLY005)funded projects for the Academic Leader and Academic Backbones,Shaanxi Normal University(no.18QNGG006)。
文摘Manganese dioxide(MnO2)is a widely used and well-studied 3-dimensional(3D)transition metal oxide,which has advantages in ultrafast optics due to large specific surface area,narrow bandgap,multiple pores,superior electron transfer capability,and a wide range of light absorption.However,few studies have considered its excellent performance in ultrafast photonics.y-MnO2 photonics devices were fabricated based on a special dual-core,pair-hole fiber(DCPHF)carrier and applied in ultrafast optics fields for the first time.The results show that the soliton molecule with tunable temporal separation(1.84 to 2.7 ps)and 600-MHz harmonic solitons are achieved in the experiment.The result proves that this kind of photonics device has goodapplications in ultrafast lasers,high-performance sensors,fiber optical communications,etc.,which can help expand the prospect of combining 3D materials with novel fiber for ultrafast optics device technology.
