The Role of Various Chlorides on Xylose Conversion to Furfural: Experiments and Kinetic Modeling

Abstract

In this paper, the catalytic activity of thirteen different metal chlorides in aqueous solution for the conversion of xylose into furfural was studied in comparison with both the auto‐ and HCl‐catalyzed reactions. A maximum furfural yield of 60.3 mol % was reached with the addition of FeCl3 to the aqueous xylose solution. However, the catalytic efficiency of FeCl3 decreased on use of birch hydrolysate as a raw material, resulting in 43.5 mol % furfural yield. The obtained experimental results were incorporated in a kinetic modeling study. The assessed reaction rates for xylose dehydration to furfural and xylose decomposition to byproducts, in the presence of AlCl3 and CrCl3 are significantly higher than during acid‐catalyzed conversion. The logarithms of the reaction rates show a linear correlation with the ionization energy as well as with the acidity of the metal ions.

A comparative study of water-immiscible organic solvents in the production of furfural from xylose and birch hydrolysate

“…The FUR yield increased from 37 mol% to 68% with an increasing time from 30 to 90 min at 190 °C when employing an aqueous to CPME phase ratio of 1:1 (Figure 11). The highest mole fraction of hydroxymethylfurfural (HMF) was 0.01 mmol ( Figure A12 in the Supporting Information), which is in agreement with previous studies when using birch hydrolysate to produce FUR from pentoses [70]. °C in 180 min was 78% in the case of CPME as an organic solvent phase.…”

Conversion of Xylose to Furfural over Lignin-Based Activated Carbon-Supported Iron Catalysts

“…However, the significantly highest furfural yield (68%) and selectivity (70%) were achieved using iron chloride as a catalyst. Our result agrees with the literature, as many studies have shown that FeCl 3 produces the highest furfural yield in water media compared to other metal halides [7,10]. The 68% furfural yield achieved in our study with FeCl 3 catalyst is also comparable to that found in other studies.…”

“…Different metal salts have been studied in the literature but it was important to perform tests in our reaction system, using microwave heating and water/MIBK media. Reactions were performed at a temperature of 160 • C, a reaction time of 1.5 h and a catalyst amount of 0.05 mmol, based on the literature [10]. Almost full xylose conversion (98%-99%) was achieved using all catalysts other than zinc chloride, which yielded only 91% conversion (Figure 2, asterisks).…”

“…The relatively low yield, high energy consumption (caused by the high, 150-240 • C, reaction temperature) and environmental concerns related to acidic process wastes are driving scientists to develop catalysts with high selectivity for furfural formation. A number of studies have used inexpensive water-soluble inorganic salts (mainly chlorides) as catalysts instead of mineral acids for xylose conversion to furfural [7][8][9][10]. Many of those studies show that FeCl 3 results in the highest furfural yields compared to other metal chlorides [7,10].…”

“…A number of studies have used inexpensive water-soluble inorganic salts (mainly chlorides) as catalysts instead of mineral acids for xylose conversion to furfural [7][8][9][10]. Many of those studies show that FeCl 3 results in the highest furfural yields compared to other metal chlorides [7,10]. Carbon-based catalysts are attractive since the carbon supports are low-cost materials with high surface area and good thermal stability and they are easily modified with functional groups [20].…”