A Study On The Preparation Of Ru/C Catalyst For Glucose Hydrogenation

During the process of glucose produces sorbitol,the traditional impregnation method and impregnation precipitation method have disadvantages.In this paper,Ru/C catalyst was prepared by liquid-phase reduction method,study on carbon modification,adsorption and reduction process,use XRD,SEM,EDS,TEM,FTIR to test.So,the structure of Ru/C catalyst was tested,and the influence mechanism in the preparation process was explored.The result as follows:(1)In the process of carbon pretreatment.Reagent,concentration,temperature and time all affect the activity of Ru/C.The influence of reagents on the activity of catalyst is HNO3>H2O>HCl>H2O2>HAC.With the increase of concentration and temperature,the activity of Ru/C catalyst first increased and then stabilized.With the increase of time,the activity of Ru/C catalyst first increased and then decreased.The optimum pretreatment condition was 0.45 mol·L-1 HNO3 at 60℃ pretreatment carbon 12 h.(2)Experimental results show that the main functions of HNO3 are remove some impurity elements(such as Ca and Cu)from the carbon,refine Ru and improve the dispersion of Ru.(3)With the increase of adsorption temperature,the activity of catalyst first increases and then decreases.The suitable adsorption temperature is 25℃.With the increase of adsorption time,the activity of catalyst decreased slowly,and the suitable adsorption time was 1.5 h.(4)With the increase of reduction temperature,the activity of catalyst decreased.With the increase of reduction time,the activity of catalyst first increased rapidly and then kept stable.With the increase of the amount of reducing agent,the activity of catalyst continued to increase.(5)The optimum reduction process is to use 9 times of theoretical amount of reducing agent at 25℃ for 4 hours.According to method B,the conversion rate of glucose was 85.63%.Acording to method A,the activity of the catalyst was tested for 30 consecutive times.The results of HPLC and chemical titration showed that the conversion rate of glucose was 100%,all products are high purity sorbitol.The catalyst has good selectivity and stability.(6)Under the suitable conditions,Ru particles in the catalyst sample are fine and evenly distributed.After 30 times of use,the Ru size changed from 2.7 nm to 2.8 nm.The change is not obvious.The dispersion of catalyst was 33.1%.In the process of carbon pretreatment,FTIR test showed that the peak position is consistent,the number of functional groups was increased.In the use stage of catalyst,the number of catalyst functional groups decreases after use.At 3442 cm-1 peak,carbon material itself contains hydroxyl or adsorbed water,it is not affected by the preparation process,but decreased during the use of catalyst.Advantages of the process:Glucose conversion is high,the purity of sorbitol product is high.In the preparation process,the operation is simple and the cost is low.The whole process takes place at 25℃.The Ru grains in the catalyst are small,and the size is 2.7 nm.