Syngas Pressure Research Articles

Effect of Equivalent Ratio and Hydrocarbon Ratio on Explosive Characteristics of Synthetic Gas

With the development of society, the importance of energy is increasing day by day, and more and more people realize the importance of energy for social development.Therefore, people began to explore energy utilization, energy exploitation, clean energy and other fields.Therefore, in order to use coal resources cleanly and efficiently and reduce the damage to the environment, the development of clean coal technology is particularly important.As a kind of clean energy, syngas has been paid more and more attention, so people pay more and more attention to the safety application of syngas. This paper explores its influence on syngas explosion by changing the equivalent ratio of syngas and the ratio of hydrogen and hydrogen.The results show that the maximum explosion pressure of syngas occurs near the equivalent ratio 1.2, the maximum explosion pressure rise rate reaches the maximum near the equivalent ratio 1.5, and the maximum explosion pressure time reaches the minimum near the equivalent ratio 1.5.The change of hydrocarbon ratio does not shift the equivalent ratio of the above result, but only changes its value. The prediction equations for predicting the maximum explosion pressure under different equivalent ratios are obtained

Simulation of Underground Coal-Gasification Process Using Aspen Plus

In order to study the underground coal-gasification process, Aspen Plus software was used to simulate the lignite underground gasification process, and a variety of unit operation modules were selected and combined with the kinetic equations of coal underground gasification. The model can reflect the complete gasification process of the coal underground gasifier well, and the simulation results are more in line with the experimental results of the lignite underground gasification model test. The changes in the temperature and pressure of oxygen, gasification water, spray water, and syngas in pipelines were studied, and the effects of pipe diameters on pipeline conveying performance were investigated as well. The effects of the oxygen/water ratio, processing capacity, and spray-water volume on the components of syngas and components in different reaction zones were studied. In addition, the change tendency of gasification products under different conditions was researched. The results indicate that: (1) The depth of injection and the formation pressure at that depth need to be taken into account to determine a reasonable injection pressure. (2) The liquid-water injection process should select a lower injection pressure. (3) Increasing the oxygen/water ratio favors H2 production and decreasing the oxygen/water ratio favors CH4 production. (4) The content of CO2 is the highest in the oxidation zone, the lowest in the reduction zone, and then increases a little in the methanation reaction zone for the transform reaction. The content of CO is the lowest in the oxidation zone and the highest in the reduction zone. In the methanation reaction zone, CO partially converts into H2 and CO2, and the content of CO is reduced. (5) The injection of spray water does not affect the components of the gas but will increase the water vapor content in the gas; thus, this changes the molar fraction of the wet gas.

One-pot hydroaminomethylation of an alkene under formation of primary amines by combining hydroformylation at elevated syngas pressure and biocatalytic transamination in water

We report a novel one-pot chemoenzymatic synthesis of primary amines, combining rhodium-catalysed hydroformylation of styrene with transaminase-catalysed enzymatic transamination. This process is starting from styrene at 50 mM substrate loading...

Efficient Interfacial Sites between Metallic and Oxidized Cobalt for Propene Hydroformylation.

Currently, the hydroformylation of short olefins is operated almost exclusively by using Rh catalysts. Considering the high cost and scarcity of rhodium resources, it is important to develop non-noble metal catalysts toward hydroformylation. Herein, we report an efficient cobalt-based catalyst rich in interfacial sites between metallic and oxidized cobalt species for the hydroformylation of short olefin, propene, under a moderate syngas pressure. The catalyst exhibited a high specific activity of 252 mol molCo-1 h-1 in toluene under 2 bar of propene and 40 bar of CO/H2 mixed gas (CO/H2 = 1:1) at 160 °C. According to mechanistic studies, the interface of metallic and oxidized cobalt species promoted the adsorption of CO and propene. Moreover, the interfacial sites lowered the energy barrier for CO* hydrogenation and C-C coupling compared with metallic cobalt.

A thermo-mechanical simulation for the stability analysis of a horizontal wellbore in underground coal gasification

The stability analysis of horizontal wells is essential for a successful underground coal gasification (UCG) operation. In this paper, a new 3D coupled thermo-mechanical numerical modeling is proposed for analyzing the stability of UCG horizontal wells. In this model, the effect of front abutment stresses, syngas pressure, syngas temperature and thermal stresses is considered to predict the mud weight window and drilling mud pressure during UCG process. The results show that the roof caving in UCG panel has a greatest impact on the stability of horizontal well. Moreover, when the time of coal gasification is increased, the well convergence increases and for more stability it is necessary to increase the drilling mud pressure. This research was carried out on the M2 coal seam in Mazino coal deposit (Iran). The results showed that the mud weight window for horizontal well drilling is between 0 and 33 MPa. The appropriate stress for the maximum stability of the horizontal well, taking all the thermal and mechanical parameters into account, is 28 MPa. The suggested numerical method is a comprehensive and consistent way for analyzing the stability of horizontal wells in UCG sites.

Regioselectivity Inversion in Hydroformylation of Aryl Alkenes with a Diphosphoramidite-rhodium Catalyst

Abstract: Rhodium catalysts for hydroformylation of aryl alkenes generally promote the formation of branched aldehydes. Here, we have demonstrated that by using a single rhodium catalyst containing a diphosphoramidite ligand derived from BINOL, it is possible to achieve the inversion of regioselectivity in the hydroformylation of aryl alkenes simply by reducing the syngas pressure or, alternatively, increasing the reaction temperature. Indeed, the hydroformylation of styrene carried out at 20 bar and 50°C resulted in 72% of 2- phenylpropanal, while at atmospheric pressure, 71% of 3-phenylpropanal was obtained. A similar linear selectivity (72-74%) was observed when the hydroformylation of styrene, pmethylstyrene, and p-methoxystyrene was performed at 10 bar and higher temperature (80°C). The regioselectivity of the hydroformylation of trans-β-methylstyrene under mild conditions (80°C, 10-20 bar) was also strongly influenced by the syngas pressure. The results of this study show that it is possible to reverse the selectivity of aryl alkenes hydroformylation with a single catalyst by simply exploring the reaction conditions. In this paper, we have shown that the inversion of the regioselectivity in the hydroformylation of aryl alkenes can be achieved using a single rhodium catalyst containing a BINOL-derived diphosphoramidite ligand by reducing the syngas pressure or, alternatively, increasing the reaction temperature.

Hydroformylation catalyzed by unmodified cobalt carbonyl under mild conditions.

Hydroformylation with unmodified cobalt carbonyl catalyst plays a crucial role in industrial production of surfactants and plasticizers. However, syngas pressures of 100 to 400 bar with reaction temperatures of 100° to 250°C are typically applied. We report here that unmodified cobalt carbonyl is a stable hydroformylation catalyst at 140°C under 30 bar of syngas. The activity was comparable to that of recently reported bisphosphine-coordinated cobalt(II) catalysts, which we could not reproduce under the reported conditions. Kinetic and in situ infrared spectroscopic studies confirmed the stability of the unmodified cobalt tetracarbonyl hydride [HCo(CO)4]. Branched internal olefins were converted to aldehydes with high regioselectivity under low syngas pressures without phosphorus ligands. Bisphosphines had a small promotional effect on the catalyst at phosphorus-to-cobalt loading ratios below 0.6.

Promising Recyclable Ionic Liquid-Soluble Catalytic System for Reductive Hydroformylation

We report here the reductive hydroformylation of methyl 10-undecenoate (issued from castor oil) in a biphasic liquid/liquid system. The rhodium/amine catalytic system is immobilized in an ionic liquid phase, whereas the olefin and the products are in a nonpolar layer. The effects of various reaction parameters (nature and concentration of amines, nature of ionic liquids, temperature and syngas pressure or composition) were studied to increase the production of primary alcohols. Under optimized conditions, potassium N,N-dimethyltaurinate salt associated with rhodium, immobilized in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, allowed us to attain 93% of alcohol yield. With only 2 equiv of amine with respect to rhodium, the catalytic system can be efficiently immobilized in the ionic liquid and recycled due to the ionic nature of the involved catalytic species.

Methanol-to-olefins catalysis on window-cage type zeolites/zeotypes with syngas co-feeds: Understanding syngas-to-olefins chemistry

Catalyst lifetime and product selectivity of methanol-to-olefins (MTO) catalysis on window-cage type zeolites and zeotypes are examined and interpreted to elucidate the critical role of high-pressure H2 and CO in MTO catalysis at conditions relevant for syngas-to-olefins (STO) conversion (H2/CH3OH >100, CO/CH3OH >100). Propylene co-feed experiments elucidate that acid-catalyzed hydrogenation reactions transpire and enhance olefins-cycle propagation by intercepting formaldehyde-mediated condensation and dehydrocyclization reaction cascades to result in an increase in catalyst lifetime (>7×) and decrease ethylene-to-propylene (∼1.5×) and ethylene-to-butenes ratios (∼1.6×) during MTO with high-pressure H2 co-feeds. CO is mechanistically relevant in increasing ethylene-to-propylene (∼1.5–3.0×) and ethylene-to-butenes ratio (∼1.7×) during MTO catalysis only at high CO (3–8 bar) and syngas pressures (24 bar, H2/CO∼2–16); at these high pressures, CO participates in carbonylation reactions to enhance aromatics-cycle propagation and enable a pathway for ethylene production via methyl acetate formation. These results suggest that high-pressure syngas introduces new catalytic pathways to distinguish MTO catalysis from STO catalysis and MTO catalysis in the presence of high-pressure syngas reagents.

Cover Feature: Cobalt‐Catalysed Reductive Etherification Using Phosphine Oxide Promoters under Hydroformylation Conditions (Chem. Eur. J. 11/2022)

Catalysis on wheels: The beneficial effects of phosphine oxide additives on cobalt-catalysed reductive etherification enable the cobalt catalyst to “skate” from substrates (left) to products (right). The promoting effect further enables a milder and more general reaction, allowing a lower temperature and syngas (H2/CO) pressure as well as a broader scope. More information can be found in the Research Article by E. V. Gusevskaya, M. Beller et al. (DOI: 10.1002/chem.202103903).

Fundamental Study of the Integrated Process of Heavy Oil Pyrolysis and Coke Gasification. Part Ii. Effect of Pyrolysis Temperature and Initial Syngas Pressure

Fundamental Study of the Integrated Process of Heavy Oil Pyrolysis and Coke Gasification. Part Ii. Effect of Pyrolysis Temperature and Initial Syngas Pressure

Selective Rhodium-Catalyzed Hydroformylation of Terminal Arylalkynes and Conjugated Enynes to (Poly)enals Enabled by a π-Acceptor Biphosphoramidite Ligand.

The hydroformylation of terminal arylalkynes and enynes offers a straightforward synthetic route to the valuable (poly)enals. However, the hydroformylation of terminal alkynes has remained a long-standing challenge. Herein, an efficient and selective Rh-catalyzed hydroformylation of terminal arylalkynes and conjugated enynes has been achieved by using a new stable biphosphoramidite ligand with strong π-acceptor capacity, which affords various important E-(poly)enals in good yields with excellent chemo- and regioselectivity at low temperatures and low syngas pressures.

Rh Particles Supported on Sulfated g-C3N4: A Highly Efficient and Recyclable Heterogeneous Catalyst for Alkene Hydroformylation

The hydroformylation of alkenes with CO and H2 to manufacture aldehydes is one of the most large-scale chemical reactions. However, an efficient and recyclable heterogeneous catalyst for alkene hydroformylation is extremely in demand in academia and industry. In this study, a sulfated carbon nitride supported rhodium particle catalyst (Rh/S-g-C3N4) was successfully synthesized via an impregnation-borohydride reduction method and applied in the hydroformylation of alkenes. The catalysts were characterized by XRD, FTIR, SEM, TEM, XPS, and nitrogen adsorption. The influence of the sulfate content, pressure of syngas, temperature, and reaction time, as well as the stability of Rh/S-g-C3N4, on the hydroformylation was examined in detail. The delocalized conjugated structure in g-C3N4 can lead to the formation of electron-deficient aromatic intermediates with alkenes. The sulphate g-C3N4 has a defected surface owing to the formation of oxygen vacancies, which increased the adsorption and dispersion of RhNPs on the surface of g-C3N4. Therefore, Rh/S-g-C3N4 exhibited an outstanding catalytic performance for styrene hydroformylation (TOF = 9000 h−1), the conversion of styrene could reach 99.9%, and the regioselectivity for the branched aldehyde was 52% under the optimized reaction conditions. The catalytic properties of Rh/S-g-C3N4 were also studied in the hydroformylation of various alkenes and displayed an excellent catalytic performance. Furthermore, the reuse of Rh/S-g-C3N4 was tested for five recycling processes, without an obvious decrease in the activity and selectivity under the optimum reaction conditions. These findings demonstrated that Rh/S-g-C3N4 is a potential catalyst for heterogeneous hydroformylation.

Aqueous olefin hydroformylation using water-soluble mono- and trinuclear N,O-chelate rhodium(I)-aryl ether precatalysts

Water-soluble, sulfonated, salicylaldiminato-aryl ether mono- (7) and trimeric (8) ligands were prepared and reacted with the [Rh(μ-Cl)(η2:η2−COD)]2 dimer to yield the corresponding water-soluble mononuclear (9) and trinuclear (10) Rh(I) complexes. These rhodium complexes were evaluated and are active as catalyst precursors in the aqueous biphasic hydroformylation of 1-octene and styrene. Optimal conditions were realised, using 1-octene as a model substrate, at 85 °C and a syngas pressure of 50 bar, where the best activity and chemoselectivity for aldehydes was obtained. Catalyst recycling was successfully conducted over 5 cycles in a biphasic medium, with a gradual loss in catalytic performance for both complexes. However, the dendrimer-stabilised trinuclear precatalyst (10) showed improved recyclability during “neat”, aqueous monophasic hydroformylation experiments, while the mononuclear precatalyst (9) showed a reduced overall performance. Both precatalysts showed sustained catalytic activity (> 450 h−1) and a total bias towards aldehyde chemoselectivity during the aqueous biphasic hydroformylation of styrene.

Fischer–Tropsch Synthesis over a Cobalt Catalyst Supported on Titania-Doped Silicon Carbide

A cobalt Fischer–Tropsch synthesis catalyst supported on titania-doped silicon carbide is synthesized and comprehensively studied by a number of physicochemical means. The dynamics of the behavior and deactivation of the catalyst was studied after its stable operation for 1500 h during continuous experimental resource testing with a periodic change in the syngas flow rate and pressure and the process temperature. This catalyst has two types of active sites, on which products with different Schulz–Flory distribution parameters form. Depending on the process regime, the effective formation of soft waxes or more high-molecular-weight products is possible.

Highly Efficient 1-Octene Hydroformylation at Low Syngas Pressure: From Single-Droplet Screening to Continuous Flow Synthesis

We present a reconfigurable flow chemistry strategy for facile transition between accelerated screening and continuous synthesis of linear aldehydes through homogeneous rhodium-catalyzed hydroformylation of alkenes. The intensified mass and heat transport rates of the utilized membrane-based flow reactor enable access to safe and desirable reaction conditions (i.e., 50 psig syngas pressure) while providing high chemoselectivity and regioselectivity of the produced aldehydes. Additionally, by conducting hydrogen–deuterium scrambling experiments, we propose a reaction mechanism for the highly efficient hydroformylation reaction in flow.

Fischer–Tropsch synthesis, the effect of promoters, catalyst support, and reaction conditions selection

This work brings the overview of Fischer–Tropsch synthesis (FTS) from catalysis point of view. The role of promoters’ type and their amount loaded into the catalyst are described and discussed for both, iron- (Cu, K, Na, S, Zr, Ni) and cobalt (Ru, Pt, Re, Zr, Ag, Rh, Ir, Au)-based catalysts, respectively, as same as the role of catalyst supports and reaction conditions. Catalyst supports discussed in this work are from the group of oxides, mesoporous silicas and zeolites, carbon-based materials, and carbides. Reaction conditions studied and discussed are reaction temperature, gas hourly space velocity of syngas and hydrogen to carbon monoxide ratio in syngas and reaction pressure. For iron-based catalysts, reaction temperature is discussed in the range of 508–613 K, while for cobalt types in the range of 468–513 K. Reaction pressure is discussed for both catalyst types up to 3 MPa. All the parameters are presented and discussed using FTS selectivity to main groups of products, such as CH4, CO2, C2–C4 hydrocarbons, and C5+ hydrocarbons together with syngas conversion degree. Detailed review of data published in articles studying FTS over iron and cobalt catalysts supplied large data set for presenting and discussion of trends and effects of aimed parameters and for their visualization in form of set of charts. This data analysis brings complex overview of basic trends of catalytic properties of cobalt and iron catalysts.

The Fischer – Tropsch synthesis with a cobalt catalyst on titania-doped silicon carbide

A cobalt catalyst supported on titania-doped silicon carbide for the Fischer – Tropsch synthesis was synthesized and comprehensively studied using various physicochemical methods. The dynamics of behavior and deactivation of the catalyst, which showed a stable operation for 1500 hours, was studied in a continuous pilot-plant lifecycle test with periodic variation of flow rate, syngas pressure and process temperature. This catalyst has two types of active sites on which products with different parameters of the Schulz – Flory distribution are formed. Depending on the process mode, the efficient formation of «soft waxes» or products with a higher molecular weight can occur.

Multitasking FeOCN Composite as an Economic, Heterogeneous Catalyst for 1‐Octene Hydroformylation and Hydration Reactions

AbstractA highly efficient multitasking FeOCN composite was synthesized in a single step by the fast heating of an Fe(III) salt and urea. The composite was confirmed by various spectroscopic and analytical techniques which include XRD, FTIR, Raman, FESEM, and XPS analysis. The composite was then investigated for various organic transformations and it was found to be excellent for the hydroformylation of 1‐octene in toluene under 50 bar syngas pressure at 95 °C. The composite was also found to be significantly active for the hydration reactions of alkynes and nitriles under acid‐ and base‐free conditions. The hydration reactions were performed in aqueous methanol at 120 °C and an excellent yield of regioselective products was obtained under optimized reaction conditions.

Butadiene hydroformylation to adipaldehyde with Rh-based catalysts: Insights into ligand effects

Rh-catalyzed hydroformylation of butadiene to adipaldehyde is a promising alternative route for producing valuable C6 compounds such as adipic acid and hexamethylenediamine. Fundamental insights into reaction pathways, aimed at enhancing adipaldehyde yield, were obtained from temporal concentration profiles and in situ ReactIR studies of butadiene hydroformylation on Rh complexes at 80 °C and 14 bar syngas (molar CO/H2 = 1) pressure in a batch reactor. Specifically, the effects of operating conditions and eight commercially available ligands on activity and selectivity were systematically investigated. It was found that the adipaldehyde selectivity is independent of the ligand/Rh ratio, rhodium concentration, butadiene concentration and syngas pressure, but significantly dependent on the type of ligand used. For example, while the DIOP ligand provided an adipaldehyde yield of ∼40% with butadiene as a substrate, the 6-DPPon ligand gave a maximum adipaldehyde yield of ∼93% with 4-pentenal as substrate. Furthermore, the adipaldehyde selectivity correlates well with the natural bite angle of the various ligands. ReactIR studies suggest that the preferential formation of the stable rhodium η3-crotyl complex with the various Rh complexes may be the main reason for the low adipaldehyde selectivity.