Sulfonic acid functionalized ß zeolite as efficient bifunctional solid acid catalysts for the synthesis of 5-hydroxymethylfurfural from cellulose.

Introduction of the sulfonic acid group into H-ß zeolite to prepare ß-SO3H bifunctional catalysts for the efficient synthesis of 5-hydroxymethylfurfural (HMF) from cellulose. Catalysts characterization, such as XRD, ICP-OES, SEM (Mapping), FTIR, XPS, N2 adsorption-desorption isotherm, NH3-TPD, Py-FTIR demonstrate the sulfonic acid group was successfully grafted onto the ß zeolite. A superior HMF yield (59.4 %) and cellulose conversion (89.4 %) was obtained in the H2O(NaCl)/THF biphasic system under 200 °C for 3 h with ß-SO3H(3) zeolite as catalyst. More valuable, ß-SO3H(3) zeolite converts other sugars and obtains ideal HMF yield, including fructose (95.5 %), glucose (86.5 %), sucrose (76.8 %), maltose (71.5 %), cellobiose (67.0 %), starch (68.1 %), glucan (64.4 %) and also converts plant material (25.1 % for moso bamboo and 18.7 % for wheat straw) with great HMF yield. ß-SO3H(3) zeolite catalyst keeps an appreciable recyclability after 5 cycles. Moreover, in the presence of ß-SO3H(3) zeolite catalyst, the by-products during the production of HMF from cellulose were detected, and the possible conversion pathway of cellulose to HMF was proposed. The ß-SO3H bifunctional catalyst has excellent potential for the biorefinery of high value platform compound from carbohydrates.

Ultralight and robust aerogels based on nanochitin towards water-resistant thermal insulators.

The development of lightweight, strong and high-performance thermal insulators from renewable biomass are highly desired for sustainable development. Here, ultralight aerogels based on renewable nanochitin with outstanding mechanical properties, excellent water-resistant, and promising thermal insulation properties are fabricated. The pristine nanochitin aerogels (PNCAs) assembled from mechanically strong carboxylated chitin nanorods are firstly prepared through acid-induced gelation and supercritical drying. The resultant PNCAs present tunable density (10-50 mg/cm3) and strong mechanical stiffness (the specific compression modulus of 30.2 MPa cm3/g) combining with low thermal conductivity (27.2 mW/m K). After a facile silylation modification, the silylated nanochitin aerogels (SNCAs) exhibit hydrophobic behavior (contact angle >130°), improved compression performance (the specific compression modulus of 65 MPa cm3/g), and promising thermal insulation property (30.5-35.8 mW/m K). Moreover, the silylated aerogel shows a negligible loss of mechanical performance when exposed to water for 12 h at 35 °C.