*2.1. Support Preparation*

Precipitation method: the supports (hereinafter denoted as Ce P and CeLa P) were synthesized by precipitation with urea at 100 ◦C with aqueous solutions of (NH4)2Ce(NO3)<sup>6</sup> (Sigma Aldrich, St Louis, MO, USA) and additionally La(NO3)3.6H2O, in the adequate amount to obtain a 5 wt % of lanthanum(Sigma Aldrich, St Louis, MO, USA); in the final sample, for the latter. The solution was mixed and boiled at 100 ◦C for 6 h. The precipitates were washed with deionized water and dried at 110 ◦C for 18 h. The material was then calcined under air flow (30 mL/min) at 650 ◦C for 3 h.

Reverse microemulsion method: the supports (hereinafter denoted as Ce M and CeLa M) were synthesized by preparing two different microemulsion systems: (A) Saline microemulsion composed by: 450 mL n-heptane 99% (Sigma Aldrich, GMBH, Riedstr, Germany), 90 mL triton X(Sigma Aldrich, St Louis, USA, MO, USA), 92 mL 1-hexanol 98% (Sigma Aldrich, St Louis, MO, USA), 50 mL aqueous solution of Ce(NO3)3.6H2O (0.5 M); (B) Basic microemulsion composed by 450 mL n-heptane 99%, 1-hexanol 98%, 90 mL Triton X-100 and 50 mL basic solution (0.5 M NaOH). The proper amount of lanthanum precursor was added to obtain a 5 wt % of lanthanum in the final sample. Both microemulsions were stirred at 100 rpm for 1 h. Then, solution B was added to solution A and was kept under stirring at 100 rpm for 24 h. The precipitates were separated by centrifugation, washed with methanol, dried at 120 ◦C for 18 h and calcined in air at 650 ◦C for 3 h.
