Biogas reforming to syngas over cu‐modified Ni‐Al‐LDH catalysts

Abstract

Ni-Al-LDH catalyst was modified with Cu to improve catalyst activity and deactivation resistance in biogas reforming. The samples were obtained by impregnation of Cu on Ni-Al previously prepared by coprecipitation, and characterized by X-ray diffractometry, N 2 physisorption, temperatureprogrammed reduction, CO 2 temperature-programmed desorption, and temperature-programmed oxidation. Catalytic tests were performed with CH 4 / CO 2 = 1.5 at 600 and 700 C in a fixed bed reactor. The characterization results revealed that the presence of Cu facilitates the reduction of Ni 2+ to Ni . The washing step influences the properties of the catalyst, since samples with low Cu content showed greater activity and stability than catalysts with high Cu content. At 700 C, the best results were obtained with the unreduced catalyst, with CH 4 conversions above 75%, because the reduction with H 2 at such condition causes catalyst sintering. No deactivation was observed at 600 C. The results achieved by the unreduced catalysts show potential for the production of H 2 as they do not require theactivation with H 2 . A mechanism for activating the catalyst with CH 4 was proposed.

Effect of Ca and Co over Ni–Al Mixed Oxides for Hydrogen Production by Ethanol Steam Reforming

“…The catalysts were prepared by continuous coprecipitation, as described in previous works. [39,[52][53][54][55][56][57][58][59][60][61][62] A nitrate solution (1 M) of the desired metals (Ca, Co, Ni, and Al) was mixed with a solution of Na 2 CO 3 (2 M) in a jacketed continuous stirred tank reactor. The mixture was kept at 50 °C and pH 8.0 AE 0.1.…”

“…Temperature programmed oxidation (TPO) analysis was performed for the spent samples using a thermobalance (TA Instruments, model SDT Q600), where 10 mg of the spent sample was exposed to airflow of 30 mL min À1 while heated at 10 °C min À1 from ambient temperature to 800 °C. [39,[52][53][54][55][56][57][58][59][60][61][62]…”

“…The temperature was monitored with a K-type thermocouple set in the middle of the bed. [39,[52][53][54][55][56][57][58][59][60][61][62] The first test was conducted at 400, 450, 500, 550, and 600 °C temperature steps with a 100 mL min À1 N 2 flow. The ethanol/ water mixture 1:3 (molar proportion) was fed by a syringe-type micropump (KD Scientific) at a 0.4 mL h À1 flow rate.…”

“…The products passed through a condenser and were analyzed online by Gas Chromatography (Varian 3600cx) using a TCD detector and a packed Porapak Q column. [39,[52][53][54][55][56][57][58][59][60][61][62] The second test was conducted at 600 °C for 8 h to evaluate the catalyst stability. The reactor was heated to 600 °C with a N 2 flow rate of 100 mL min À1 .…”

“…The reactor was heated to 600 °C with a N 2 flow rate of 100 mL min À1 . After stabilizing the temperature, the ethanol/water mixture 1:3 (molar proportion) was fed, and after 15 min, online analyses were carried out every 10 min for 8 h. [39,[52][53][54][55][56][57][58][59][60][61][62] Ethanol conversion (X EtOH ) and P i product selectivity (S Pi ) were calculated through Equation ( 4) and ( 5), respectively:…”