Sodium hydroxide (naoh)

All reagents used in the experiments were of analytical grade and used without further purification. The reagents used were weighed on a Shimadzu analytical scale, model AUY220, to prepare the solutions. The solutions were prepared using ultrapure water (resistivity 18.0 MΩ cm) obtained by the Thermo Scientific Barnstead™ Nanopure™ system (Waltham, MA, USA).
The reagents Na₂HAsO₄·7H₂O (CAS: 10048-95-0) and NaAsO₂ (CAS: 7784-46-5) were provided by Sigma-Aldrich (St. Louis, MO, USA), and the reagents NaOH (CAS: 1310-73-2), HNO₃ (CAS: 7697-37-2), CH₃COOH (CAS: 64-19-7), and HCl (CAS: 7647-01-0) were purchased from Vetec (Brazil). Rhodium (Ra) (CAS: 7440-14-4) and multi-elementary solution were obtained from PerkinElmer (Waltham, MA, USA).

12-molybdophosphoric acid (H₃PMo₁₂O₄₀.H₂O, HPMo, Mo = 63.08%, VETEC, Darmstadt, Germany), sulfuric acid (H₂SO₄, 98%, ISOFAR, Duque de Caxias, Rio de Janeiro, Brazil) and hydrochloric acid (HCl, 37%, Fmaia, Belo Horizonte, MG, Brazil), cetyltrimethylammonium bromide (C₁₆H₃₃(CH₃), CTABr, Vetec, Rio de Janeiro, Brazil), ethanol (EtOH, 98%, Nuclear, São Paulo, SP–Brazil) and sodium hydroxide (NaOH, VETEC, Rio de Janeiro, Brazil), eugenol (EugOH, 99% Sigma Aldrich, Darmstadt, Germany) and acetic anhydride (AA, Nuclear, São Paulo, SP–Brazil). All chemical reagents and solvents were analytical grade and used without further purification. The flint kaolin was kindly provided by the UFPA Institute of Geology from the Capim River Region (Pará Brazil).

Carbon was produced utilizing glycerol 99% from Vetec (São Paulo, São Paulo), sulfuric acid >98% from LabSynth (Diadema, São Paulo) and acetone from Cosmoquimica Indústria e Comércio (Barueri, São Paulo). Characterization techniques used KBr 99.5% from Sigma-Aldrich (São Paulo, São Paulo), NaOH 99% from Vetec (São Paulo, São Paulo), NaHCO₃ 99.5% from Sigma-Aldrich (São Paulo, São Paulo), HCl 36.5–38.0% from Vetec (São Paulo, São Paulo). Catalytic tests were performed with D(-)fructose >99,9% from Sigma Aldrich (São Paulo, São Paulo) and Dimethylsulfoxide >99,9% from Synth (Diadema, São Paulo). All chemicals were used as received and without any treatment.

Aluminum can seals (10.0 g) were digested in an acid solution (1.1 mol L⁻¹, 1000 mL) of hydrochloric acid (HCl, P.A., Synth) for about 24 h (Figure 1). The final solution containing the Al³⁺ ions had a pH 0.5 [29 (link)]. To obtain the boehmite phase, the pH was corrected by adding sodium hydroxide (NaOH, Vetec, 3.0 mol L⁻¹) until the pH reached 8, causing a white solid to precipitate. The solid was vacuum filtered and oven-dried at 70 °C for 24 h [29 (link)].

Two natural bentonite samples from Cubati (BC) and Lagedo (BL) cities located in the state of Paraíba (Northeastern Region of Brazil) were used as starting materials for the preparation of hybrid catalysts. The chemical composition of the samples was obtained by the Dispersive Energy X-ray spectroscopy (EDS) technique (see Table 2). The fraction of clay enriched with montmorillonite less than 2 μm was supported with H₃PMo₁₂O₄₀·xH₂O (designated by HPMo). The reagents were ethanol (EtOH, Nuclear, 99.5%, AR), methanol (Nuclear, AR), 12-phosphomolybdic acid (HPMo, Mo ≥63%, Vetec, Rio de Janeiro, Brazil, AR), hydrochloric acid, AR), sodium bicarbonate (Na₂CO₃, Vetec, AR), sodium bicarbonate (NaHCO₃, Vetec, AR) and sodium hydroxide (NaOH, Vetec, AR). All reagents were used as supplied. The DDPO is a residue (viscosity at 60 °C =12.296 mm² s⁻¹; density at 60 °C = 0.862 g mL⁻¹; water content <0.5%; oxidative stability >150 h; acidity index =177.15 mg KOH g⁻¹) consisting of 84% fatty acids (42% palmitic, 41% oleic, 10% linoleic, 5% Stearic, 1% Lauric and 1% myristic), 12% by weight of triglycerides, diglycerides and monoglycerides and 4% by weight unsaponifiable matter, corresponding to 4% of the product formed in the refining of palm oil [9 (link),39 (link)], kindly donated by Companhia Refinadora da Amazônia, Agropalma S/A (Brazil).