Abstract
Xylose and cellulose acetate were prepared by hydrolysis and acetylation of hemicellulose and cellulose in landscaping biomass waste (pine) by dilute acid hydrolysis and acetylation, respectively. The obtained solid residue was rich in lignin that mainly contains three phenylpropane structural units and can be used to prepare aromatic chemicals under hydrothermal conditions. In this work, the synthesis of high value-added aromatic aldehydes (vanillin, syringaldehyde, and p-hydroxybenzaldehyde) from the solid residue (rich in lignin) by mild catalytic oxidation was studied. The oxidation degradation of the solid residue in NaOH solution to produce aromatic aldehydes was investigated by single factor experiment. The optimum reaction conditions were obtained as follows: 175 ℃, 90 min, 3.0 g solid residue, 100.0 ml NaOH solution (concentration of 2.0 mol/L), and oxygen pressure of 1.5 MPa. Under these conditions, the total yield of aromatic aldehydes from pine branch residue was 23.8 wt%.
Highlights
Greening waste refers to the falling branches, fallen leaves, flower decay, grass debris, tree and shrub cutting and other plant residues produced by human pruning or natural withering, which is called green waste garbage or garden waste by some researchers [1,2]
It can be seen from the above Table that different catalysts have different effects on the yield of aromatic aldehydes
CuSO4 is the best catalyst, and the total yield of aromatic aldehydes is as high as 24.4%, and the effect of iron salt is good
Summary
Greening waste refers to the falling branches, fallen leaves, flower decay, grass debris, tree and shrub cutting and other plant residues produced by human pruning or natural withering, which is called green waste garbage or garden waste by some researchers [1,2]. Most of the wet oxidative degradation of lignin is used to produce aromatic aldehydes, such as vanillin (VLA), syringaldehyde (SA) and phydroxybenzaldehyde (PHBA). These compounds have many applications, especially vanillin is widely used in food, cosmetics and pharmaceutical industries as condiments and spices. Among these products, only vanillin has been industrialized. The synthesis of high value-added aromatic aldehydes (vanillin, syringaldehyde, and p-hydroxybenzaldehyde) from the solid residue (rich in lignin) by mild catalytic oxidation was studied
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