Santos Daniel, Silva Ubiratan F, Duarte Fabio A, Bizzi Cezar A, Flores Erico M M, Mello Paola A
Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil.
Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil.
Ultrason Sonochem. 2018 Jan;40(Pt B):81-88. doi: 10.1016/j.ultsonch.2017.04.034. Epub 2017 Apr 25.
In this work, the use of ultrasound energy for the production of furanic platforms from cellulose was investigated and the synthesis of furfural was demonstrated. Several systems were evaluated, as ultrasound bath, cup horn and probe, in order to investigate microcrystalline cellulose conversion using simply a diluted acid solution and ultrasound. Several acid mixtures were evaluated for hydrolysis, as diluted solutions of HNO, HSO, HCl and HCO. The influence of the following parameters in the ultrasound-assisted acid hydrolysis (UAAH) were studied: sonication temperature (30 to 70°C) and ultrasound amplitude (30 to 70% for a cup horn system) for 4 to 8molL HNO solutions. For each evaluated condition, the products were identified by ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-ToF-MS), which provide accurate information regarding the products obtained from biomass conversion. The furfural structure was confirmed by nuclear magnetic resonance (H and C NMR) spectroscopy. In addition, cellulosic residues from hydrolysis reaction were characterized using scanning electron microscopy (SEM), which contributed for a better understanding of physical-chemical effects caused by ultrasound. After process optimization, a 4molL HNO solution, sonicated for 60min at 30°C in a cup horn system at 50% of amplitude, lead to 78% of conversion to furfural. This mild temperature condition combined to the use of a diluted acid solution represents an important contribution for the selective production of chemical building blocks using ultrasound energy.
在这项工作中，研究了利用超声能量从纤维素制备呋喃类平台化合物，并证明了糠醛的合成。评估了几种系统，如超声浴、杯式换能器和探头，以便研究仅使用稀酸溶液和超声作用下微晶纤维素的转化情况。评估了几种用于水解的酸混合物，如HNO₃、H₂SO₄、HCl和HCOOH的稀释溶液。研究了以下参数在超声辅助酸水解（UAAH）中的影响：对于4至8mol/L的HNO₃溶液，超声处理温度（30至70°C）和超声振幅（杯式换能器系统为30至70%）。对于每个评估条件，通过超高效液相色谱与高分辨率飞行时间质谱联用（UPLC-ToF-MS）对产物进行鉴定，该方法可提供有关生物质转化所得产物的准确信息。通过核磁共振（¹H和¹³C NMR）光谱确认了糠醛的结构。此外，利用扫描电子显微镜（SEM）对水解反应后的纤维素残渣进行了表征，这有助于更好地理解超声引起的物理化学效应。经过工艺优化，在杯式换能器系统中，使用4mol/L的HNO₃溶液，在30°C下以50%的振幅超声处理60分钟，糠醛转化率达到78%。这种温和的温度条件与稀酸溶液的使用相结合，对于利用超声能量选择性生产化学结构单元具有重要意义。
