Recently, scientists from Guangzhou Institute of Energy Conversion (GIEC), Chinese Academy of Sciences (CAS) developed a new approach for the preparation of cellulosic ethanol. By using graphene layers encapsulated nickel (Ni@C) catalysts with the aid of phosphoric acid (H3PO4) in water, one-pot direct conversion of cellulose to ethanol via non-noble metal catalysts was realized for the first time, which provides a new way for industrialized production of cellulosic ethanol with high efficiency and low cost. 

As an important bulk chemical, bio-ethanol is widely applicable in chemical and medical industries, especially in fuel as gasoline additive. It is expected that more than 30% of transportation fuel will be derived from biomass by the year of 2030, for the goal of CO₂ emissions reduction. As an excellent additive, bio-ethanol shall become a key player as it can be directly used as a drop-in bio-fuel in gasoline. 

The traditional way for ethanol preparation is dependent on enzymatic hydrolysis-fermentation, showing long production cycle, expensive enzyme cost and easy deactivation by poisoning. It is also economically challenged due to the theoretical yield ceiling of 67 mol%, and limited concentration of 10wt%-12wt%, not to mention CO₂ simultaneously released during conversion from sugars to ethanol. 

In contrast to the bio-production of cellulosic ethanol, the direct conversion of cellulose to ethanol by chemical approach may tune the reaction pathway during the cellulose transformation through catalyst design, avoiding CO₂ formation to achieve high atom efficiency.  

The research team led by Prof. MA Longlong developed a one-pot way for direct cellulose hydrogenolysis into ethanol using graphene layers encapsulated nickel (Ni@C) catalysts with the aid of phosphoric acid (H₃PO₄) in water. A 69.1% of ethanol yield was obtained, which is comparable to the theoretical value by glucose fermentation. And 8.9 wt% ethanol concentration was obtained with the increased cellulose concentration. This work demonstrates a chemo-catalytic approach for high yield and high concentration of ethanol production from renewable cellulosic biomass. 

“This work, for the first time, demonstrates a chemo-catalytic approach for high yield and high concentration of ethanol production from biomass using non noble metal catalyst. The development of more efficient catalysts could enhance the ethanol production, leading to feasibility of direct conversion of cellulose into ethanol economically.” MA says. 

The work was financially supported by the National Natural Science Foundation of China (51536009 and 51576199), the Natural Science Foundation of Guangdong Province (2017A030308010), the DNL Cooperation Fund, CAS (DNL180302), the National Key R&D Program of China (2018YFB1501402 and 2017YFE0106600) and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01N092).  

The paper was recently published online in ChemSusChem as the cover paper entitled“Selective Cellulose Hydrogenolysis to Ethanol Using Ni@C Combined with Phosphoric Acid Catalysts” ( DOI: 10.1002/cssc.201901110). 

Figure: Direct Biomass Hydrogenolysis into ethanol  (ChemSusChem cover paper. Imaged by WANG Haiyong)

Contact:
Dr. LIU Qiying
Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences
(http://english.giec.cas.cn/)
Guangzhou 510640, China
Tel: 86-20-37029721
E-mail: liuqy@ms.giec.ac.cn