The Effects of Different Ratios of Sonochemically Assisted Nickel Oxide and Zirconium Oxide Catalysts in Syngas Production

Abstract

Heterogeneous catalytic cracking is currently one of the most effective ways for both reducing tar content and enhancing hydrogen (H 2 ) content in syngas at relatively low temperature, besides being environmental friendly. Sonochemical treatment has also been shown to lower reaction times with enhanced reaction rate and enables production of particles with high surface area. Two different types of metal oxides, which are Nickel Oxide (NiO) and Zirconium Oxide (ZrO 2 ) at combinations of 1:1, 1:2 and 2:1 ratios with Zeolite NaY as the supporter were synthesized via sonochemical treatment. The catalysts were then characterized using X-Ray Diffraction (XRD), Temperature Programmed Reduction in H 2 /Argon (TPR-H 2 ), Brunauer-EmmettTeller surface measurement (BET), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). From SEM and TEM analysis, nickel tends to agglomerate and form globular shapes, zirconium forms coral-like branching structure and Zeolite NaY forms stacks of cubic clumps. The most promising NiO to ZrO 2 ratio for syngas production is 1:1 because it removes the most reactive oxygen during hydrogen reduction at 0.83 x10 21 atoms/g, has small crystallite size at 56.90 nm and has the highest surface area for maximum contact with the reactants at 506.52 m 2 /g. Generally, sonochemical treatment also reduces the catalysts crystallite size (54.83 nm) and increases the catalysts surface area (506.52 m 2 /g) and oxygen removal (0.83 x10 21 atoms/g) as well as lowers the reduction temperature (637 K) which is favourable in term of production cost.Keywords: heterogeneous catalysts, nickel oxide, zirconium oxide, zeolite, syngas Abstrak Perekahan pemangkin heterogen adalah salah satu cara terkini yang paling efektif untuk mengurangkan kandungan tar dan juga meningkatkan kandungan hidrogen (H 2 ) di dalam singas pada suhu rendah, di samping mesra alam sekitar. Rawatan sonokimia juga telah dibuktikan dapat mengurangkan masa tindak balas di samping meningkatkan kadar tindak balas dan membolehkan penghasilan partikel dengan luas permukaan yang tinggi. Dua jenis besi oksida berbeza, iaitu Nikel Oksida (NiO) dan Zirkonium Oksida (ZrO 2 ) dalam kombinasi nisbah 1:1, 1:2 dan 2:1 dan Zeolit NaY sebagai penyokong dihasilkan melalui rawatan sonokimia. Katalis -katalis tersebut kemudian dianalis menggunakan pembelauan sinar-X (XRD), Penurunan Suhu Berprogram (TPR-H 2 ), pengukuran permukaan Brunauer-Emmett-Teller (BET), Mikroskop Imbasan Elekron (SEM) dan Mikroskop Elektron Transmisi (TEM). Daripada analisis SEM dan TEM, nikel cenderung untuk bergumpal dan membentuk glob besar, zirkonium membentuk struktur seperti karang bercabang dan Zeolit NaY membentuk lapisan kubik. Nisbah NiO kepada ZrO 2 yang paling atom/g, mempunyai saiz kristal yang kecil iaitu 56.90 nm dan mempunyai luas permukaan yang paling tinggi pada 506.52 m 2 /g untuk kontak maksimum dengan bahan tindak balas. Umumnya rawatan sonokimia juga mengurangkan saiz kristal katalis (54.83 nm) dan meningkatkan luas permukaan pemangki...