Contents lists available at ScienceDirect Catalysis Communications journal homepage: www.elsevier.com/locate/catcom Short communication Facile synthesis of size-controlled Ag supported on WO 3 nanorods and their application as novel and active catalyst in oxidant-free dehydrogenation of benzyl alcohols Bappi Paul a , Sachin Sharma a , Debraj D. Purkayastha b , Siddhartha S. Dhar b , Rajaram Bal a, ⁎ a Catalytic Conversion & Processes Division, CSIR-Indian Institute of Petroleum, Dehradun 248005, India b Department of Chemistry, National Institute of Technology Silchar, Silchar 788010, Assam, India ARTICLE INFO Keywords: Ag-WO 3 nanorod Polyethylene glycol Size-tunable Oxidant-free Benzyl alcohols ABSTRACT A new and simple strategy for the size-tunable synthesis of silver supported tungsten oxide nanoparticles (NPs) was reported. Polyethylene glycol (PEG) of molecular weights 400 and 4000 was used as surfactant to tune the size of nanoparticles. These as-synthesized Ag/WO 3 nanomaterials were characterized by XRD, FT-IR, TGA, TEM, SEM, EDX, ICP-AES, XPS, and BET analysis. The material synthesized in the presence of PEG 4000 is ~10 nm metallic silver nanoparticles (Ag NPs) supported on tungsten oxide (WO 3 ) nanorods with diameters between 20 and 40 nm. These nanomaterials are very effective catalysts in oxidant-free dehydrogenation of benzyl alcohols. 1. Introduction Synthesis and characterization of inorganic nanomaterials have re- ceived great interest and importance in various fields of science and technology [1–3]. It has also been observed that due to the synergistic effect, catalytic efficiency boost to great extent when nanomaterials doped with another metal [4]. Controlled and easy synthesis of Ag supported on WO 3 nanomaterials still poses great challenges despite significant research efforts. Development of a facile method for the in- situ synthesis of Ag supported on WO 3 nanomaterials with desired morphology, shape and size, is considered a challenging proposition. It is relevant to mention that polyethylene glycol (PEG) with ordered and uniform chained structure can act as a reducing agent as well as a surfactant to control morphology and size of the nanomaterials [5–7]. Previously PEG was used individually as a surfactant and reducing agent for the synthesis of WO 3 and Ag NPs. However, there has been no report on the use of PEG for the in-situ synthesis of Ag/WO 3 composites. Numerous catalysts have been reported for the environmentally benign oxidation of alcohols. With the growing concern of economic and environmental acceptability, a process using atom economic cata- lyst system that does away with molecular oxygen or hydrogen per- oxide for the conversion of alcohols to carbonyl compounds would be more attractive from an environmental standpoint. Such oxidant-free methodology is particularly useful from practical and commercial viewpoint due to (i) elimination of H 2 O as by-products, which often cause work-up difficulty, (ii) its usefulness for O 2 and sensitive func- tional groups, (iii) production of H 2 , that may be used as feedstock for energy generation (iv) its ability to prevent over oxidation to carboxylic acids [8–10]. A number of homogeneous as well as heterogeneous transition metal catalysis has been reported for oxidant-free dehy- drogenation of alcohols [11–13]. A few homogeneous Rh [14], Ru [15] and Ir [16] based catalysts have been reported, but most of them suffer from the requirement for excess amount of base, high temperatures (> 200 °C), intense energy source, difficult catalyst synthesis and ma- nipulation, difficulties in catalyst reuse, and high price. There are several heterogeneous catalyst based on Ru [17], Au [18], Ni [19], Cu [20] and Co [21] have also been documented in the literature and in most of the cases, the catalytic systems suffer from air sensitivity, low catalytic activity, harsh conditions, difficult catalyst synthesis, high catalyst loading, relatively poor activity and selectivity. Moreover, TOFs of these catalysts for production of aldehydes are not very high and thereby leaves scope for improvement. All these aforementioned limitations of literature reported on homogeneous and heterogeneous catalysts for dehydrogenative oxidation of alcohols provide enough scope for improvement in synthesis of a new catalytic system capable of exhibiting very strong performance. We report herein, a novel and fa- cile method for the synthesis of Ag/WO 3 using PEG that plays a dual role of surfactant as well as reducing agent and studied their catalytic activity for dehydrogenation of benzyl alcohols. https://doi.org/10.1016/j.catcom.2019.105804 Received 17 May 2019; Received in revised form 22 August 2019; Accepted 27 August 2019 ⁎ Corresponding author. E-mail address: raja@iip.res.in (R. Bal). Catalysis Communications 132 (2019) 105804 Available online 28 August 2019 1566-7367/ © 2019 Published by Elsevier B.V. T