The present status, challenges and prospects for the selective conversion of syngas to chemicals and fuels are summarized based on the analysis of published articles with different key words. The background information, topics, and achievements of the symposium are introduced. Finally, a brief summary of the selected papers in the special issue is given.

Catalysts are the core of heterogeneous catalytic reactions. Due to the complexity of catalytic reactions, humans have very limited knowledge of the active phases of the catalysts. The structure-performance relationship of the catalyst during the reaction is important for understanding the catalytic reaction process and improving the catalyst. The Operando technique can monitor the evolution of the catalyst structure in real time, detect the reaction products online and promote the rational design of industrial catalysts. Firstly, this paper introduces the development history of catalytic reaction and dynamic in-site characterization technique, and then describes the Operando Raman technique in Fischer-Tropsch synthesis (FTS) and CO2 hydrogenation combining with recent research progress. The application of typical catalytic reactions demonstrate the structural evolution process and structure-performance relationship of the catalyst under different pretreatment and precursor conditions. However, the temporal resolution and spatial resolution of the current Operand technique still need to be further improved. In addition, the Operando technique still has vast development potential in solid-liquid and gas-liquid catalytic reactions.

η-Fe2C is discriminated as the active phase of the low-temperature Fischer-Tropsch synthesis (FTS). CO adsorption and activation on this catalyst is the key step during the Fe-based FTS. In order to gain insight to this process, spin-polarized density functional theory calculations were performed to investigate the CO adsorption and activation on both the perfect and defective η-Fe2C(011) surfaces. The calculated results show that the most stable configuration of CO adsorption is the top site binding with Fe atom, while the precursor state for CO dissociation is the 3F site. The direct CO dissociation can hardly occur due to the high CO dissociation barrier, and the H-assisted CO dissociation via HCO intermediate is proposed to be as the dominant activation pathway. Furthermore, with the formation of C-vacant site, the 4F site works as the most stable adsorption and activation site, with largely decreases of direct CO dissociation barriers, leading to the similar overall CO activation energy barriers for both direct and H-assisted CO dissociation via formation of HCO. Therefore, they may occur simultaneously with the C-vacant site over the η-Fe2C(011) surface.

A serial of Fischer-Tropsch synthesis catalysts (Fe-Cu-K-SiO2) was prepared by the co-precipitation method with varied pH of 6~8. The properties of the catalysts, i.e. crystal phase, particle size, pore structure, reducibility and carburization, were studied by XRD, N2 adsorption, H2-TPR, and Mssbauer spectroscopy. The catalysts were evaluated for Fischer-Tropsch synthesis under typical industrial conditions. The results indicate that the increase of pH values increases the particle size and decreases the surface area, which inhibit the reduction and carburization of the catalysts. As a result, a lower CO conversion and a lower selectivity of CH4 but a higher selectivity of CO2 and C5+ products were obtained in Fischer-Tropsch synthesis. By correlating the Mssbauer characterization with catalytic results, the CO conversion is revealed to be dependent on the Fe5C2 phase while CO2 selectivity is related to Fe3O4 phase over the catalyst.

Hybrid catalysts combined Zn-ZrO2 oxide with different zeolites were synthesized and used for the direct conversion of syngas. It was found that the Zn-ZrO2/H-ZSM-5 catalyst exhibited higher CO conversion as well as gasoline fuel selectivity than other catalysts. The effects of reaction temperature and contact time on catalytic performances over Zn-ZrO2 oxide and Zn-ZrO2/H-ZSM-5 were further investigated, and the results suggested that methanol and dimethyl ether intermediates were firstly formed over Zn-ZrO2 and then further transformed into gasoline fuel over H-ZSM-5 zeolite. The Zn/Zr molar ratio and Si/Al molar ratio of H-ZSM-5 over Zn-ZrO2/H-ZSM-5 bifunctional catalyst were also studied. The results showed that the Zn/Zr molar ratio at 1∶32 and the Si/Al ratio of H-ZSM-5 at 200 over Zn-ZrO2/H-ZSM-5 were beneficial to the conversion of syngas and the formation of gasoline fuel. Moreover, the catalyst was stable, there was no significant deactivation in 100 h.

Catalyst materials are widely used in industry and nearly 90% of the chemical products were produced via catalysis. Among heterogeneous catalysis, catalysts must have strong mechanical strength in order to stand for the dynamic changes of mechanical stress that might occur during reactions. Thus, to optimize the forming technology and processing parameters, the ways to characterize mechanical strength of each particle are very important for large-scale catalyst preparation. Herein, this paper clarified the type of catalysts, the way for powder forming, characterization methods for the formed catalyst and the methods to detect the strength and defects of formed catalysts. Meanwhile, it also demonstrated a novel defect detection tool (MicroCT) with recorded pictures.

LaCo0.7Cu0.3O3 was supported on SiO2 according to the incipient wetness impregnation method combined with citrate complexing method. The prepared catalyst precursors were characterized by XRD, BET, H2-TPR and TEM.The catalytic performance for higher alcohols synthesis from syngas was conducted in a slurry reactor, which was compared with that in fixed-bed reactor. After reduction, the catalyst precursor favoured to form nanoparticles of Cu-Co alloy highly dispersed on SiO2 and modified with La2O3. In slurry reactor, the selectivity to C2+OH was much higher, which may be attributed to the effect of liquid slurry of paraffin for suppressing the desorption of methanol and the formation of hot-spots. Under the experimental condition of 900 to 1 500 mL/(gcat·h), 3 MPa, H2∶CO∶N2=8∶4∶1 and 250 ℃，C2+OH in the total alcohols was more than 95% in weight.

The alkaline promoter K modified Cu/Zn/La/ZrO2 catalysts were prepared using the coprecipitation method, and used for the synthesis of isobutanol from syngas in a fixed bed reactor. The effects of K promoter and reaction temperature on the catalytic performance were investigated in combination of BET, XRD, CO2-TPD, NH3-TPD and CO-TPD characterizations. The results indicated that addition of K inhibited the dispersion of each component, leading to the larger particle size. Meanwhile, reduction peaks of CuO shifted to the higher temperature. However, addition of K led to an increase in the amount of weak acidic sites and weak base sites, which have remarkably close relationships with CO adsorption and space-time yield (STY) of alcohol. Moderate weak acid and base sites were beneficial to improve the STY of total alcohols and the selectivity of isobutanol in total alcohols.

MoO2-Mo2N composite catalyst was prepared by modifying bulk phase Mo2N via RF plasma technique, and its catalytic performance in higher alcohols synthesis from syngas was investigated. The catalysts were characterized by XRD, TEM, XPS and CO-TPD. It was found that during the plasma treatment, the bulk phase Mo2N can recombine with the surface oxygen atoms, which resulted in more active sites on the catalyst. Also there is certain interaction between MoO2 and Mo2N. The catalytic performance of the prepared MoO2-Mo2N composite catalyst is improved compared with that of the bulk phase Mo2N. At the reaction temperature of 350 ℃, the CO conversion rate, the alcohol selectivity, and the alcohol space-time yield reach 32.7%, 34.03%, and 79.5 mg/(g·h) respectively.

The PdO/SnxCeyO2 catalysts were synthesized by the co-precipitation-impregnation method.XRD, N2 adsorption-desorption, CO-TPD and CO-DRIFT techniques were used to investigate the structural and surface properties of the catalysts, and their catalytic activity by CO oxidation were evaluated.The results show that the CO oxidation activity of the catalysts is irrelevant with the surface area, but directly correlates with the reactivity of surface lattice oxygen species. Compared with the Pd/Sn0.7Ce0.3O2 catalyst，the higher reactivity of surface lattice oxygen species on the Pd/Sn0.3Ce0.7O2 catalyst plays a vital role in better CO oxidation performance at low temperatures. The in-situ DRIFT spectra of CO adsorption show that, the PdO species can be reduced by CO even at room temperature and form the Pd0/Pd+ species. The linearly bonded CO-Pd0 is the dominate adsorption species. Furthermore, compared with the inert pre-treatment method, the oxidative pre-treatment method facilitates the oxidation of CO and decreases the formation of carbonates.

CH4-CO2 reforming has attracted growing attention because it can efficiently utilize two greenhouse gases and convert them into valuable syngas with low H2/CO ratio. Ni based catalysts have been extensively investigated for their high activity and low cost, but they also suffer from coke deposition and sintering problems. In this paper, recent progresses in Ni-based reforming catalysts are summarized and analyzed taken into account reaction kinetics, reaction thermodynamics and formation mechanism of carbon deposition, with a particular emphasis over promoters and their roles. Finally, the bottleneck and future development trend of the titled reaction are briefly described.

Steam gasification of coal is one of the efficient ways to produce syngas from coal. Steam gasification performance of four kinds of Mongolia coal was comprehensively investigated in this paper. The composition and the evolution rates of syngas were studied during steam gasification. The influence of thermodynamic equilibrium on the gasification reaction of four coal samples was also discussed. As research shown that the steam gasification performance of Baganuur coal (BN), Nalaik coal (NL) and Alagtogoo coal (AT) were significantly higher than that of Tawantolgoi coal (TT). The syngas contained high H2 and low CO contents producing by BN, NL and AT, however, TT produced the syngas which contain high CO content, since the water-gas shift reaction (WGSR) was carried out completely with high H2 and low CO production rates in steam gasification process of BN, NL and AT. Syngas of high CO content was produced from steam gasification of TT due to its low WGSR. Moreover, the thermodynamic equilibrium was one of the main factors led to the differences of steam gasification characteristics for the four kinds of Mongolia coal.

A monolithic Pd/ZSM-5/Cordierite catalyst was prepared by coating the active Pd/ZSM-5 component on the Cordierite support with Polyvinyl alcohol (PVA) solution as an assistant agent,and its structure and physicochemical properties were characterized by XRD, N2 sorption, SEM, XPS and ICP-AES. The Pd/ZSM-5/Cordierite catalyst was applied in the combustion of lean methane and the effects of PVA concentration, active component loading mode and Pd loading on the coating stability and catalytic performance in lean methane combustion were then investigated. The results indicate that a stable coating of the active Pd/ZSM-5 component can be achieved on the Cordierite support when the mass fraction of PVA in the PVA solution is 3%. With an overall Pd loading of 1.12‰ and Pd/ZSM-5 as the coating powder, the (Pd/ZSM-5)/Cordierite catalyst exhibits excellent performance in the lean methane (1%) combustion.The reaction temperatures to reach a methane conversion of 10%, 50% and 90% are as low as 271, 337 and 385 ℃, respectively. Moreover, the monolithic (Pd/ZSM-5)/Cordierite catalyst also displays excellent stability in a long term test of 435 h for the lean methane combustion at different temperatures, suggesting its enormous potential for the application in the mitigation of lean methane through catalytic combustion.

CuO/TiO2 and CuO/N-TiO2 catalysts with 30% Cu loading were prepared by deposition-precipitation method using copper chloride as copper source, sodium hydroxide as precipitant, and TiO2 and N-TiO2 as supports. Combined with the characterization of N2 physical adsorption-desorption， X-ray diffraction(XRD), H2-temperature programmed reduction(H2-TPR), X-ray photoelectron spectroscopy (XPS) , CO Fourier transform infrared spectroscopy (CO-IR), and etc, the effects of N doping on the structure of TiO2 supported CuO catalyst and the catalytic performance of formaldehyde ethynylation were studied. The results show that N-doped TiO2 presented more Ti3+ species and oxygen vacant sites, which increased the interaction between CuO and the carrier and was conducive to the dispersion of CuO species. In the process of ethynylation, CuO is transformed into highly dispersed Cu+ active species in situ, and the catalyst shows high catalytic activity and stability.

A series of Cu-SiO2 samples with different contents of CuO was synthesized via the one-pot evaporation induced self-assembly method, and was evaluated as a catalyst for the gas-phase dehydrogenation of cyclohexanol to cyclohexanone. The catalysts were characterized by XRD, TG-DSC, TEM, and N2 adsorption-desorption at low temperatures. At the reaction temperature of 300 ℃, the Cu-SiO2 catalyst containing 10% CuO showed the best performance among the investigated samples, i.e., the initial conversion of cyclohexanol was over 90% and the selectivity of cyclohexanone was over 99%. From the results of the long-term reaction (50 h) and the regeneration of the used catalyst, the sintering of the metallic Cu particles was revealed to be responsible for the catalyst deactivation. These findings are important for the further development of a high-performance Cu-based catalyst for the titled reaction.