The gas-phase deoxydehydration of 2,3-butanediol to butene was investigated in aplug flow reactor over SiO 2 -supported vanadium oxide, g-alumina, P/ZSM-5, andM gO catalysts with acid/bases ites of varying strengths. 5wt% vanadium on SiO 2 (i.e.,5V/SiO 2 )s howedt he best performance with 100 %conversion and up to 45.2 %b utene selectivity.T he combination of weak acid sites and polymericV O x surfaces peciesp rovided the 5V/SiO 2 catalystw ith bifunctional capabilities to achieve both dehydration and transfer hydrogenation, which allowed it to catalyze the deoxydehydration of 2,3-butanediol to butene even in the absence of H 2 .A s2 ,3-butanediol is ac ommon yet underutilized biomassp roduct, this reactionm ay provide av iable route for ab iomass-to-chemicals application for 2,3butanediol.Upgrading of biomass to fuels and chemicals is important for sustainable human development, and intense studiesa re being undertaken to find new technologiest oc onvert the large amount of availablebioderived oxygenates into fuels and chemicals. [1] The vicinal diol 2,3-butanediol (2,3-BDO) is ac ommon biomass product that is synthesized by using bacteria sugars derived from biomass feedstock such as corn starch. [1c] It has great potentialt or eplaces ynthetic 2,3-BDO in the market owing to its cost effectiveness relative to the chemical hydrolysis of 2,3-butene oxide. Whereas its other isomers such as 1,4-butanediola nd 1,3-butanediol have been widely studied for their conversion into other chemicals such as tetrahydrofuran and butyrolactone, [2] these cyclization reactions are not availablef or 2,3-BDO owing to the vicinal positiono fi ts OH groups.T hus, 2,3-BDO is much less studied than 1,4-and 1,3-butanediol, although it could follow multiple oxidation, reduction, and dehydration pathways. [1c,d] The dehydration of 2,3-BDO mainly produces butanone (also knowna sm ethyl ethyl ketone, MEK) and 2-methylpropanal (MPA) through aE 1/E2 mechanism followed by 1,2-rearrangement by hydride and methyl shifts, respectively. [2a] This is readily achieved on acid sites, such as those availablei np hosphate catalysts or zeolites. [3] However,t he doubled ehydration of 2,3-BDO to butadiene is more challenging than that of 1,4-butanediol because the carbonyl compounds MEK and MPAf ormed from 2,3-BDOa re more difficult to dehydrate further than enol compounds such as 3-buten-1-ol, whicha re typically formed from 1,4-butanediol. [4] Alternatively,Z heng et al. recently reported aC u/ZSM5 catalyst that could convert2 ,3-BDOi nto butene in the presence of an excess amount H 2 withoutf urther hydrogenation to butane. [5] In this study,t he gas-phase conversion of 2,3-BDO was performed over SiO 2 -supported vanadium oxide, g-alumina, P/ ZSM-5, and MgO catalysts with acid/base sites of varying strengths. We show that ad eoxydehydration pathway of 2,3-BDO to butene in the absence of H 2 exists that proceeds through ah ydrogen-donor mechanism from 2,3-BDO to MEK over vanadium oxide (VO x )s urfaces ites.The ammonia temperature-programmed d...