Fixed-bed continuous flow

Huybrechts, W., Mijoin, J., Jacobs, P.A. et al. (2003) Development of a fixed-bed continuous-flow high-throughput reactor for long-chain n-alkane hydroconversion. Appl. Catal. A Gen., 243, 1. 

The ethane reaction was studied in a fixed bed continuous-flow reactor made of quartz (100 mm x 27 mm o.d.).Thc reacting gas mixture consisted of 20% C2H6, 40% N2O (or O2) and He as diluent. The flow rate of the reactants was usually 50... 

The most active formulation (ZSNbPt) was tested in a conventional reactor using as feedstream a mixture of light n-alkanes [n-pentane (20 wt%), n-hexane (60 wt.%) and n-heptane (20 wt%)] to simulate an industrial stream. Experiments were carried out in a conventional reaction system using a fixed-bed continuous -flow reactor. Reaction was carried out under the same conditions as the poisoning resistance experiments. The activity and selectivity of this catalyst (Fig. 5.13) have been compared with those obtained with sulfated zirconia impregnated with platinum (ZS). Fig. 5.13 represents the evolution of the conversion with reaction temperature. Clearly, the reactivity of the n-paraffm follows the order n-heptane > n-hexane > n-pentane for both catalysts, as expected when taking into account the adsorption heats of the different hydrocarbons [34]. 

Catalytic tests have been performed in a high pressure fixed bed continuous flow "Catatest unit from VINCI Technologies, France, with the Safanyia atmospheric residue. The experimental conditions employed were a total pressure of 8 MPa, a reaction temperature of 380°C, a liquid hourly space velocity... 

Catalytic reactions were carried out with 2 g catalyst placed in a fixed-bed continuous-flow reactor at the gas space velocity (F/W) of 1440 ml/g h under the reaction pressure of 200 KPa. The products were withdrawn periodically from the outlet of the reactor and analyzed by gas chromatography with a 4 m long squalane column and detected by a hydrogen flame ionization detector. The conversion and selectivity were calculated on the carbon number basis. 

Catalytic activity. Methylcyclopentane (Aldrich, 98 % purity) conversion was carried out at atmospheric pressure and 623 K of temperature in a fixed bed continuous flow reactor. The conversion was kept lower than 15 %. The saturation temperature of the reactant was 273 K. The reaction products were analyzed on-line using a Perkin-Elmer 8410 gas chromatograph, equipped with a FID detector and a 50 m fused silica capillary column with methyl-5%-phenyl-silicon coating. 

Methane conversion was performed in a conventional fixed-bed continuous flow reactor operated under atmospheric pressure. The reactor consisted of a quartz, U type tube of 9 mm internal diameter. The amount of catalyst used for a test run was about 0.25 g, which was held in place by quartz wool plugs. The reactor was placed in an electric furnace with approximately 20 cm of the quartz-filled tube serving as a preheater. Before the reaction the catalysts were pretreated in an oxygen flow at 1048 K for 1 h. The reactant mixture of CH4 and 5% O2 in He was adjusted to meet several CH4/O2 ratios and a total flow rate of about 1.2 dm /h, keeping constant the oxygen... 

Catalyst Evaluation. The powdered molecular sieves were evaluated following the treatment described above, without further activation. The 1-hexene isomerization and Cg aromatic isomerization tests were conducted in tubular, fixed bed, continuous flow microreactors. The catalyst bed contained one gram molecular sieve powder and one to three grams of similarly sized quartz chips used as diluent. The reactor was heated to the chosen reaction temperatures in a fluidized sand bath, and the reaction temperature was monitored by a thermocouple located m the catalyst bed. Typical runs lasted 3 to 5 hours during which samples were collected every 30 minutes. 

Activity of the catalysts for the cyclodehydrogenation reaction of acetaldehyde and ammonia to produce 2 4-picolines was evaluated in fixed bed continuous flow reactor under atmospheric pressure at various temperature.The method for testing the activity of the catalysts was adopted as described(8). 

Catalytic properties were examined in a fixed bed continuous flow microreactor at atmospheric pressure with Hg resp. N2 as carrier gases (flow rate 10 1 h applying the conversion of ethylbenzene and the isomerization of m-xylene as probe reactions on one gram of the binder-free zeolite (0.35 - 1.0 mm). The shape selectivity was tested as described elsewhere [7]. ... 

These experiments have been performed in a classical fixed bed continues flow reactor system [5]. The catalyst sample (0.2 g) diluted with SiC was charged in a 12.6 mm i.d. tubular stainless-steel reactor, between two layers of SiC. The thermocouple well was placed in the axis of the reactor. The various CsHj - O2 - N2 mixtures were prepared by means of mass flow controllers and the concentrations of products were determined by gas chromatography, using PORAPAK Q columns (2 m 1/8") for preliminary separation and CARBOXEN 1000 column (4m 1/8") for O2, N2, CO, CO2 and an other PORAPAK Q column (2 m 1/8") for CsHg and C3H6. 

PCE was oxidized in a fixed-bed continuous flow reactor. The reactor was a 6-mm-o.d. Pyrex glass tube operated in the down flow mode. A reactant mainly containing air with 30 10,000 ppm of PCE was fed into the reactor charging 60/80 mesh size catalyst at a flow rate of 600 ml/min to avoid mass transfer resistance. The reaction temperatures were maintained at 350 °C under atmospheric pressure as a typical reactor condition [9]. The feed and product streams of the reactor were analyzed by on-line H.P. 5890A gas chromatography (GC) with TCD and FID detectors. The steady-state conversion of PCE was calculated based upon the difference between inlet and outlet concentrations of PCE. It has also been examined that more than 90% of PCE is converted to CO and CO2 by carbon balance. More detailed experimental procedures are described elsewhere [2]. 

At this stage, we were particularly interested in employing the dual-anchored catalysts to examine the alkenolysis [66] of natural seed oil derivatives in batch and continuous-flow processes. Utilizing stirred-tank, batch reactions with as ht-tle as 5 ppm of the supported catalysts, TONs for the production of methyl 9-decenoate were obtained in excess of40 000. The catalysts were also found to be active under fixed-bed, continuous-flow conditions unfortunately, the same levels of activity observed under batch conditions were not translated to the continuous-flow processes. When alternative reactions and substrates under continuous-flow... 

The authors also describe the use of 96 in a fixed-bed, continuous-flow process. A mixture of Af-tosyl diallylamine in CH2CI2 was circulated through the catalyst bed at 40 C over a 5-h period, resulting in complete conversion to product however, after washing the catalyst bed and repeating the process a second time, the conversion was only 79%. A third recycle resulted in no product formation at all. This reveals that catalyst leaching and/or stability were a major problem under the reaction conditions, and that the electrostatic immobilization was largely ineffective for the described continuous-flow application. 

Activity of LSCO powders fOT CO oxidation was measured using a fixed-bed continuous flow microteactor with 0.2 g of LSCO calcined at 800 C. A gas mixture containing CO (0.5%), O2 (0.25%) and helium was flowed through the reactor at the contact rate of 3.33 g/cm sec and analyzed by gas chromatography. The CO conversion and CO2 selectivity were calculated on the basis of the concentration of helium used as the internal standard. 

Kinage et showed that the 5 wt% Na/CeOj catalyst is one of the best catalysts for high glycerol conversion vdth high selectivity for hydroxyacetone at 350°C (Table 13.6). Other by-products are propanoic acid, ethylene glycol, 1,2-propanediol and allyl alcohol, with a selectivity below 10%. Glycerol conversion was carried out on a fixed-bed continuous-flow reactor at 350°G. For all catalysts, glycerol conversion decreased initially up to 8 h and then became stable. 

Synthesis of fatty acid methyl esters from rapeseed oil was carried out in a fixed bed continuous flow reactor at 60°C with 1 g of catalyst pellets, a molar methanol to oil (triglyceride) ratio of 40 and at liquid hourly space velocity of 6.5 h. ... 

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