Kinetic and Infrared Spectroscopy Study of Hydrodeoxygenation of 2-Methyltetrahydrofuran on a Nickel Phosphide Catalyst at Atmospheric Pressure

Abstract

Understanding the reactions of heteroatomic cyclic compounds is essential for developing good catalysts for the upgrading of bio-oils into liquid fuels. The present study presents the reaction network of 2-methyltetrahydrofuran (2-MTHF, C5H10O), a bio-oil model compound, on silica-supported nickel phosphide at 0.1 MPa and 300 °C. Contact time experiments showed that 2-MTHF reacted to first form 1-pentanol and 2-pentanol, then n-pentanal, 2-pentanone, and 1- and 2-pentenes, and finally n-pentane. The observation is consistent with a reaction network in which adsorption of 2-MTHF is followed by rate-determining ring-opening steps on the more hindered side (path I) or the more open side (path II) to first produce adsorbed alcohols. The alcohols then transform into adsorbed aldehyde, ketone, and pentene species which can simply desorb or react to produce the final product n-butane (decarbonylation of adsorbed n-pentanal) or n-pentane (hydrogenation of adsorbed pentenes). Kinetic modeling of the proposed reaction network gave good agreement with the experimental data and predicted that path I intermediates would be more numerous than path II intermediates on the surface. A series of in situ FTIR results gave further support for the mechanism with the presence of the CO and CC bands of the adsorbed aldehyde/ketone and alkene species. Transient experiments gave evidence for the model calculations that predicted more plentiful path I surface species.

Metal Phosphides and Phosphates‐based Electrodes for Electrochemical Supercapacitors

“…Nishimura et al provided the long‐awaited experimental evidence for a curved one‐dimensional chain of lithium motion and explained the Li extraction/insertion mechanism, as shown in Figure . Among the cathode materials, olivine structured LiMPO 4 cathodes deliver a flat voltage, excellent thermal and cycling stability, which is attributed to the Li extraction/insertion from the unique ordered orthorhombic structure consisting of close‐packed phosphate anions with corner and edge‐sharing MO 6 and LiO 6 octahedrons . LiMPO 4 also exhibits a strong PO covalent bond in the tetrahedral (PO 4 ) 3− that inhibits oxygen loss thereby enhancing device safety .…”

“…Among the cathode materials, olivine structured LiMPO 4 cathodes deliver a flat voltage, excellent thermal and cycling stability, which is attributed to the Li extraction/insertion from the unique ordered orthorhombic structure consisting of close‐packed phosphate anions with corner and edge‐sharing MO 6 and LiO 6 octahedrons . LiMPO 4 also exhibits a strong PO covalent bond in the tetrahedral (PO 4 ) 3− that inhibits oxygen loss thereby enhancing device safety . These properties have made them highly suitable and promising for battery‐type capacitors .…”

“…[49] LiMPO 4 also exhibits a strong PO covalent bond in the tetrahedral (PO 4 ) 3− that inhibits oxygen loss thereby enhancing device safety. [49] These properties have made them highly suitable and promising for battery-type capacitors. [42] For lithium transition metal phosphates, a variety of cation substitutions have been studied, where iron and vanadium offer promising characteristics for electrodes.…”

“…Phosphorus is a multivalent nonmetal of the nitrogen group, which is also one of the most useful and well‐established donor atoms in coordination chemistry . There is a large group of phosphorus compounds, including metal phosphides and metal phosphates, some of which have been studied for better performing electrodes for energy storage and other applications, such as in lithium ion batteries, supercapacitors, and catalysts . Indeed, phosphorus can react with most of the elements in the periodic table to form a diverse class of phosphides .…”

“…[31] There is a large group of phosphorus compounds, including metal phosphides and metal phosphates, some of which have been studied for better performing electrodes for energy storage and other applications, such as in lithium ion batteries, [42][43][44][45] supercapacitors, [46][47][48] and catalysts. [49][50][51] Indeed, phosphorus can react with most of the elements in the periodic table to form a diverse class of phosphides. [52] The phosphorus frameworks show a high flexibility, which endows metal phosphides with several stoichiometries, a wide range of compositions, and various crystal structures.…”