Direct Conversion of Wheat Straw Components into Furan Compounds Using a Highly Efficient and Reusable SnCl₂-PTA/β Zeolite Catalyst

It is highly desirable to develop a heterogeneous catalyst that is both efficient and recyclable for the simultaneous acquisition of 5-hydroxymethylfurfural (HMF) and furfural from lignocellulose feedstock. Herein, a series of (x)SnCl₂-PTA/β catalysts (x = 10, 15, 20, and 25 wt %) were prepared and characterized using ICP-AES, XRD, SEM, N₂ adsorption-desorption, XPS, NH₃-TPD, and Py-FTIR techniques. It was found that (20)SnCl₂-PTA/β catalyst having a suitable acid density, acid ratio, and texture structure contributed to the furan compound formation from carbohydrate components of wheat straw. Under optimal conditions, up to 71% of furfural and 30% of HMF were simultaneously obtained from wheat straw in a water/tetrahydrofuran biphasic system, while the byproducts formed were identified as soluble C₄-C₁₅ molecules and insoluble humins. More importantly, the (20)SnCl₂-PTA/β catalyst was still capable of providing moderate furan compounds yields after four cycles, and its catalytic performance could be partially restored by simple reimpregnation.