Carboxen 1010 plot

A continuous
flow fixed-bed quartz tubular reactor (4 mm, inner diameter) was used
to perform the rWGS reaction under atmospheric pressure. The catalyst
(with a particle size between 50 and 100 μm) was activated under
the reactive feed up to 700 °C. The space velocity was 3 ×
10⁵ mL_N·h^–1·g^–1 or 6 × 10⁵ mL_N·h^–1·g^–1, and the vol. feed composition
was 60% H₂, 30% CO₂, and 10% N₂.
The outlet gas stream was analyzed online by gas chromatography (HP
6890), equipped with a column Carboxen 1010 PLOT (SUPELCO) and with
a thermal conductivity detector. N₂ was used as an inert
standard for quantification. The catalysts were tested for about 6
h between 500 and 700 °C. A durability study was also performed
with the most active and selective catalyst composition at 700 °C
(for 96 h of reaction in continuous operation). The kinetic study
was performed with the catalyst Ni0.07/Ce0.9La0.1 at a space velocity
of 428,571 mL_N·h^–1·g^–1 (H₂/CO₂ = 2 molar and 10% N₂) at
700, 725, 750, and 775 °C for the calculation of the activation
energy. The determination of reaction orders for CO₂ and
H₂ was carried out at 750 ° C and under the following
H₂/CO₂ ratios: 1.5, 2, 2.5, and 3.

The chemical oxygen demand (COD), pH, and solids (total solids, TS; volatile suspended solids, VSS; and total volatile solids, TVS) were measured in accordance with standard methods [24 ]. The glucose concentration was measured with an enzymatic GOD-PAP method [25 ].
The biogas hydrogen content was determined by gas chromatography (GC-2010, Shimadzu, Japan) using a thermal conductivity detector (TCD) with argon as the carrier gas, and the column was packed with Supelco Carboxen 1010 Plot (30 m × 0.53 mm i.d.) [26 ]. A gas meter (Type TG1; Ritter Inc., Germany) was used to measure the amount of hydrogen generated.
The concentrations of volatile fatty acids (VFA) and alcohols were also measured using a gas chromatography system (GC-2010, Shimadzu, Japan) that was equipped with FID and COMBI-PAL headspace injection (AOC 5000 model) and a HP-INNOWAX column (30 m × 0.25 mm i.d. × 0.25 µm film thickness) [26 ].

In tube, SPME was essentially performed as described in our previous works [24 (link),29 (link)]. A GC capillary column (60 cm × 0.32 mm i.d.) as an extraction device was connected between the injection needle and injection loop of the autosampler. The capillary column was threaded through a 1/16 inch polyetheretherketone (PEEK) tube with a 2.5 cm long, 330 μm inner diameter and connected using standard 1/16 inch stainless steel nuts, ferrules and connectors. Supel-Q PLOT (Supelco, Bellefonte, PA, USA), Carboxen 1010 PLOT (Supelco), CP-Sil 5CB (Varian Inc., Lake Forest, CA, USA), CP-Sil 19CB (Varian), CP-Wax 52CB (Varian), and Quadrex 007-5 (Quadrex Corporation, Woodbridge, CT) were used to compare extraction efficiencies. The control of extraction, desorption, and injection was programmed by the autosampler software (Table S2) [24 (link),29 (link)].