*Article* **Highly Selective Syngas/H<sup>2</sup> Production via Partial Oxidation of CH<sup>4</sup> Using (Ni, Co and Ni–Co)/ZrO2–Al2O<sup>3</sup> Catalysts: Influence of Calcination Temperature**

**Anis Hamza Fakeeha <sup>1</sup> , Yasir Arafat <sup>1</sup> , Ahmed Aidid Ibrahim <sup>1</sup> , Hamid Shaikh <sup>2</sup> , Hanan Atia 3,\*, Ahmed Elhag Abasaeed <sup>1</sup> , Udo Armbruster <sup>3</sup> and Ahmed Sadeq Al-Fatesh 1,\***


Received: 7 February 2019; Accepted: 28 February 2019; Published: 6 March 2019

**Abstract:** In this study, Ni, Co and Ni–Co catalysts supported on binary oxide ZrO2–Al2O<sup>3</sup> were synthesized by sol-gel method and characterized by means of various analytical techniques such as XRD, BET, TPR, TPD, TGA, SEM, and TEM. This catalytic system was then tested for syngas respective H<sup>2</sup> production via partial oxidation of methane at 700 ◦C and 800 ◦C. The influence of calcination temperatures was studied and their impact on catalytic activity and stability was evaluated. It was observed that increasing the calcination temperature from 550 ◦C to 800 ◦C and addition of ZrO<sup>2</sup> to Al2O<sup>3</sup> enhances Ni metal-support interaction. This increases the catalytic activity and sintering resistance. Furthermore, ZrO<sup>2</sup> provides higher oxygen storage capacity and stronger Lewis basicity which contributed to coke suppression, eventually leading to a more stable catalyst. It was also observed that, contrary to bimetallic catalysts, monometallic catalysts exhibit higher activity with higher calcination temperature. At the same time, Co and Ni–Co-based catalysts exhibit higher activity than Ni-based catalysts which was not expected. The Co-based catalyst calcined at 800 ◦C demonstrated excellent stability over 24 h on stream. In general, all catalysts demonstrated high CH<sup>4</sup> conversion and exceptionally high selectivity to H<sup>2</sup> (~98%) at 700 ◦C.

**Keywords:** Al2O3; bimetallic catalyst; syngas; methane; partial oxidation; ZrO<sup>2</sup>
