Ga–Ni supported catalytically active liquid metal solutions (SCALMS) for selective ethylene oligomerization

Non-precious metal supported catalytically active liquid metal solutions exhibit attractive performance in ethylene oligomerization. It is found for the Ga–Ni system on silica that the performance depends strongly on the applied Ga/Ni ratio. Ga-rich systems forming liquid alloys exhibit a far higher Ni-based catalytic activity than solid intermetallic compounds or Ni nanoparticles.

The resulting solid was calcined at 550 °C overnight.

Elemental analysis and Ga/Ni-ratio evaluation
The Ga and Pt loading of the prepared catalysts was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using a Ciros CCD (Spectro Analytical Instruments GmbH). The solid samples were digested in 3:1:1 volumetric ratio of concentrated HCl:HNO 3 :HF using microwave heating up to 220 °C for 40 min (CAUTION: HF is extremely harmful, relevant safety precautions must be taken). The instrument was calibrated for Ni (231.604 nm) and Ga The catalytic experiemnts were performed in a continuous tubular fixed-bed reacor setup. A schematic illustration of the plant setup is shown in Figure S1. Electical heating lines and inlet flows were controlled remotely using LabVIEW software on a local PC. The inlet flows were controlled by mass flow controllers (MFCs) from Bronkhorst® EL-FLOW series. The inlet gas was mixed in the mixer (M-1) before being sent through the reactor (R-1), alternatively the by-pass.
R-1 was heated by a Horst HMT electrical heating jacket. The pressure was increased by means of a back pressure regulator (BPR).
The product stream was analyzed by gas chromatography using a Agilent 7890A on-line GC equipped with two GC coulums in casade (a CP-WAX (25 m x 0.330 mm) and a Gas Pro (30 m x 0.320 mm)) and a flame ionization detector (FID).
Mole fractions x i are calculated from peak areas and calibration factors determined for every substance. The conversion of ethylene (X ethylene ) (1), the selectivities (S i ) (2) and the C4 productivity (P C4-alkenes ) (3) were calculated as follows: (1) Selectivity: Productivity:

ASPEN Plus ® simulations for thermodynamic butene isomer distribution
The isomerisation of C4 products of an ethylene oligomerisation was simulated using the chemical process software Aspen Plus ® (version V10). The objective of these simulations were to determine the equilibria between the three structural isomers but-1-ene, trans-but-2-ene and cis-but-2-ene, allowing for comparison between experimentally obtained values and thermodynamic predictions.
Predictive Redlich Kwong-Soave (PSRK) property method was chosen following the guidelines of the Aspen Plus® manual. PSRK is recommended for gas-processing, refinery and petrochemical applications. Additionally, test simulations were also conducted over a wide range of temperatures (0-500 °C) and overall pressures (1-20 bar).
The process flowsheet comprised one main feed stream containing pure but-1-ene that was directed to an "RGibbs" type reactor, which is based on the minimisation of Gibbs free energy approach in convergence calculations, as shown in Figure S2. No reaction equations were provided. Instead, only expected compounds for various assumptions were defined in the outlet stream of the reactor, namely but-1-ene, trans-but-2-ene and cis-but-2-ene. Figure S2. Main flowsheet of the simulation performed in Aspen Plus software. The feed stream consists of pure but-1-ene at 260 °C and 6 bar flowing into an RGibbs type reactor at 2 kmol h -1 . The reactor operates at 260 °C and 6 bar. Here all potential reactions involving but-1-ene, trans-but-2-ene and cis-but-2-ene can take place.

Temperature Programmed Reduction (TPR) of Ga-Ni SCALMS catalyst
To investigate the reduction phenomena during H 2 pretreatment of the Ga-Ni SCALMS catalyst, temperature programmed reduction (TPR) were performed. The reduction of fresh Ga 67 Ni/SiO 2 under 20% H 2 in Ar up to 500 °C are shown in Figure S3.