Coke Content Research Articles

Characterization and Synthesis of Molybdenum Metal Precursors for Hydrocracking Reaction of Vacuum Residues.

In this study, Molybdenum precursors were synthesized with Triphenylphosphine, 1,2-Bis(diphenylphosphino)ethane, Pyridine, 2,2-Bipyridine as a ligands. The molybdenum precursors was used for Hydrocraking reaction of Vacuum Residue (VR). Hydrocracking reactions were carried out under the 430 °C and H₂ pressure of 80 bar in an 100 ml high pressure reactor. New Molybdenum precursors were tested and their activities were compared with Mo-octoate. The Molybdeum-Phosphine precursor showed the best performances, high yield and low coke contents (below 0,5 wt%), in of hydrocracking for VR. To characterize the physicochemical properties of Moprecursor catalyst, various characterization techniques (NMR, XPS) were carried out. We confirmed that cokes in the reactor were contained the P atoms derived from ligand of Mo-precursor after hydrocracking of VR.

Tuning SAPO-34 with a tailor-designed zwitterionic amino acid for improved MTO performance

Silicoaluminophosphate SAPO-34 zeotypes have been hydrothermally synthesized by using a tailor-designed zwitterionic amino acid of 3-hydroxy-4-triethylaminobutyric acid (Et-LC). The unnatural zwitterionic amino acid possessing both triethyl ammonium cationic moiety and anionic carboxylate group promoted SAPO-34 crystallization, allowed to decrease acidity of the as-obtained SAPO-34 catalysts, and slightly generated mesopores without affecting the microporosity. While natural amino acids either induced polymorphism due to the amino or ammonium moiety incommensurate with the chabazite unit, or showed inability to create mesopores because of the non-deprotonated carboxylic group, thus failing to meet the stringent SAPO-34 synthetic requirements of neutral pH, high temperature and appropriate templates. The Et-LC mediated SAPO-34 crystals were demonstrated to be much more effective in catalyzing the methanol to olefin (MTO) reactions with lifetime improved to 533 min, the ethylene plus propylene selectivity preserved at 81%, and coke content decreased to 8%, in comparison to those of the conventional microporous SAPO-34 zeolite of 389 min, 81%, and 17.5%. • Natural amino acids failed to create hierarchical SAPO-34. • An unnatural amino acid of Et-LC generated mesopores in SAPO-34 with reduced acidity. • The designed Et-LC bears cationic triethyl ammonium and anionic carboxylate. • The optimized SAPO-34 exhibited improved catalytic performance in MTO reaction.

Phosphorus-tuned nickel as high coke-resistant catalyst with high reforming activity

Here we demonstrate that phosphorus (P) can affect both reforming and coking of alumina-supported nickel (10 wt% Ni with respect to alumina) at 750 °C and 1 atm. The P-containing catalysts were prepared by incipient wetness co-impregnation. Compared with the P-free nickel catalyst, the reforming activity is enhanced but the coke content decreases 8-fold at Ni:P atomic ratio of 4; the latter further reduces 55-fold at a ratio of 2, without a substantial decline in the reforming activity. Phosphorus not only improves nickel dispersion but also reduces the surface acidity and facilitates CO2 activation. At high P loadings, a portion of nickel transforms into nickel oxide during reforming. Besides tuning the reforming and coking activity, phosphorus changes the behavior of carbon crystallization. In methane pyrolysis and dry reforming, filamentous carbon occurs on the P-free catalyst but it is absent on the P-containing catalyst.

Effect of the two-stage process comprised of ether extraction and supercritical hydrodeoxygenation on pyrolysis oil upgrading

In this research, Ni-based catalysts with different supports (HBeta and HZSM-5) were prepared via the impregnation method and subsequently tested for the catalytic hydrodeoxygenation (HDO) of crude pyrolysis oil (CPO) using supercritical methanol (MeOH). The Ni/HBeta showed a better catalytic performance than Ni/HZSM-5, resulting in a 43.81% deoxygenation degree of CPO. In addition, the ether extraction of CPO was carried out to remove its heavy fraction and improve the efficiency of the upgrading process. A high-quality refined oil was achieved after using the combined physicochemical treatments of ether extraction and supercritical catalytic HDO. The upgrading efficiency was evaluated in terms of the degree of deoxygenation, carbon residue value, water content, higher heating value, and distribution of products. The effect of the type of supercritical solvent on the catalytic HDO performance of Ni/HZSM-5 was evaluated by replacing MeOH with ethanol (EtOH). The results showed that when MeOH was substituted with EtOH, the yields of the gaseous and solid products were significantly reduced, while the yield of liquid products was considerably increased. Meanwhile, the content of coke deposited on the catalysts was analyzed using thermogravimetric analysis, and the coke compositions were evaluated using Fourier-transform infrared (FTIR) spectroscopy. While the minimum catalytic coke content was obtained using Ni/HBeta in the supercritical HDO of CPO, the minimum coke content was observed using Ni/HZSM-5 in the upgrading of ether-extracted pyrolysis oil (EEPO). The FTIR results revealed that the coke deposited on the catalysts was mainly formed through condensation, rearrangement, and hydrogen transfer mechanisms.

Assessment of product yields and catalyst deactivation in fixed and fluidized bed reactors in the steam reforming of biomass pyrolysis volatiles

The performance of fixed and fluidized bed reactors in the steam reforming of biomass fast pyrolysis volatiles was compared, with especial attention paying to the differences observed in catalysts deactivation. The experiments were carried out in continuous regime in a bench scale unit provided with a conical spouted bed for the pyrolysis step. They were carried out on a Ni-Ca/Al2O3 commercial catalyst and under optimum conditions determined in previous studies, i.e., pyrolysis temperature 500 °C, reforming temperature 600 °C and a steam/biomass ratio of 4. Moreover, the influence of space time was analysed in both reforming reactors. The fixed bed reactor showed higher initial conversion and H2 yield, as it allowed attaining a H2 yield higher than 90 % with a space time of 10 gcat min gvolatiles−1. However, a space time of 15 gcat min gvolatiles−1 was required in the fluidized bed to obtain a similar H2 yield. Moreover, the fixed bed also led to lower catalyst deactivation. Catalyst deactivation was mainly related to coke deposition, and higher coke contents were observed in the catalysts used in the fluidized bed reactor (1.2 mgcoke gcat−1 gbiomass−1) than those in the fixed bed one (0.6 mgcoke gcat−1 gbiomass−1). Therefore, the differences in the performance of the two reactors were analysed and their practical interest was discussed.

Operating conditions to maximize clean liquid fuels yield by oligomerization of 1-butene on HZSM-5 zeolite catalysts

Abstract The effect of operating conditions has been extensively studied for the selective oligomerization of 1-butene to clean synthetic liquid fuels. HZSM-5 zeolite (SiO2/Al2O3 ratio = 30–280) based catalysts provided with a hierarchical porous structure have been tested in a fixed bed reactor under the following conditions: 175–325 °C; 1.5–40 bar; space time, 0.5–6 gcatalyst·h molC−1. Special attention has been paid to individual and lumped gaseous and liquid product distribution (which have been characterized by gas chromatography, GC × GC/MS and simulated distillation), as well as to catalyst stability, by performing long duration experiments (20 h). An optimum region to maximize both naphtha (C5-11, >40%), and diesel (C12-20, >20%) yields has been established at 250–275 °C and 30 bar for space time values of 2–4 gcatalyst h molC−1. Furthermore, the catalysts have tended to a pseudo-stationary deactivation state after 5 h on stream, where the coke deposited on the spent catalysts is mainly composed of adsorbed bulky oligomers (determined by TPD-N2), with low coke contents ∼1.0–1.5 wt% (determined by TPO).

Controlling the Evolution of Active Molybdenum Carbide by Moderating the Acidity of Mo/HMCM-22 Catalyst in Methane Dehydroaromatization

Effect of framework Bronsted Acidity by varying SiO2/Al2O3 ratio (SAR) of HMCM-22 zeolite is studied with respect to the formation of active molybdenum carbide and its anchoring over zeolite (HMCM-22) channels of Mo/HMCM-22 catalyst tested for methane dehydroaromatization (MDA) reaction. For this purpose, HMCM-22 is synthesized by conventional methods with varying SAR (30, 40 & 55) and is studied for MDA reaction with 5 wt% Mo loading. XRD, BET, NH3-TPD, H2-TPR, 27Al MAS NMR, Raman spectroscopy and XPS techniques are used to characterize 5Mo/HMCM-22 catalyst having different SAR. XPS analysis of carburized 5Mo/HMCM-22 (SAR-30, 40 & 55) catalyst confirms that higher content of molybdenum carbide (Mo2C) forms over HMCM-22 channels at SAR-30 as compared to SAR-40 and SAR-55 due to effective binding of initial MoOx species. Interaction of initial MoOx species with HMCM-22 zeolite framework is analyzed using 27Al MAS NMR and Raman spectroscopic studies which confirm that MoOx species bind differently at SAR-30, 40 and 55 which affects the catalytic performance. Lower reducibility of MoOx species at SAR-30 confirms that MoOx species strongly interact with HMCM-22 channels at SAR-30 as confirmed by H2-TPR study. Maximum transformation of MoOx species into active molybdenum carbide over HMCM-22 at lower SAR (30) during carburization results in higher activity of 5Mo/HMCM-22 (SAR-30) catalyst with lower coke content.

Gas-phase dehydration of glycerol to acrolein over different metal phosphate catalysts

We conducted a comparative study of gas phase dehydration of glycerol to acrolein over aluminium phosphate, iron phosphate and nickel phosphate catalysts prepared by a simple replacement reaction method (AlP, FeP and NiP). The textural properties, acid amounts, acid types, and coke contents of the samples were studied. The results showed that all metal phosphate catalysts remained in an amorphous state. The glycerol conversion was proportional to the acid amount of metal phosphate catalyst in the glycerol dehydration reaction. Higher value of B/L was more likely to produce acrolein. Among the metal phosphate catalysts, FeP showed superior performance due to its suitable textural and acid properties. After 2 h on stream, high glycerol conversion (96%), acrolein selectivity (82%) and acrolein yield (79%) were achieved on the FeP catalyst at 280 °C. The catalyst deactivation was ascribed to carbon deposition on the catalyst surface blocking the active sites during the glycerol dehydration reaction.

Pd-modified beta zeolite for modulated hydro-cracking of low-density polyethylene into a paraffinic-rich hydrocarbon fuel

The catalytic properties of a microporous beta zeolite and Pd-loaded analogue were assessed in the cracking of low-density polyethylene (LDPE). The idea behind this study was to investigate the potential of zeolite beta from a different perspective, aiming at producing a hydrocarbon fuel, i.e. formed by saturated hydrocarbons, without the addition of external H2 but using the self-generated hydrogen, or hydrogen-transfer reactions. For this, a catalytic system was carefully prepared and compared to the bare beta zeolite; a protonic Pd-containing beta zeolite has a similar texture, structure and acidity features as in the base zeolite. The characterisation showed that this catalyst was achieved. The operando FTIR catalytic results indicated that the Pd-beta zeolite reaches a high selectivity towards the C2-C5 and aromatics fractions, with better control of the composition of the C2-C5 fraction leading to high isoparaffinic content, and a relatively low share of olefinic compounds. Additionally, the retardation in the coke forming reactions was evidenced, due to the high Pd-hydrogenation efficiency. Further insights were rationalized about the coke content and the catalyst auto-regeneration. From the process point of view, it was found that the use of a beta zeolite having well-dispersed Pd is an effective way to upgrade the LDPE into a paraffinic-rich hydrocarbon fuel.

Catalytic Longevity of Hierarchical SAPO-34/AlMCM-41 Nanocomposite Molecular Sieve In Methanol-to-Olefins Process.

SAPO-34/AlMCM-41, as a hierarchical nanocomposite molecular sieve was prepared by sequential hydrothermal and dry-gel methods studied for catalytic conversion of methanol to light olefins. Pure AlMCM-41, SAPO-34, and their physical mixture were also produced and catalytically compared. Physicochemical properties of materials were mainly investigated using XRD, N2 isothermal adsorption-desorption, FESEM, FT-IR, NH3-TPD, and TG/DTG/DTA techniques. Micro-meso hierarchy of prepared composite was demonstrated by XRD and BET analyses. Catalytic performance of materials illustrated that the methanol conversion of the prepared composite was about 98% for 120 min, showing a higher activity than the other catalysts. The initial reaction selectivity to light olefins of the composite was also comparable with those for the other catalysts. Furthermore, the results revealed that SAPO-34/AlMCM-41 preparation decreased the concentration and strength of active acid sites of the catalyst which could beneficially affect the deposition of heavy molecular products on the catalyst. However, as observed, the prepared composite was deactivated in olefins production faster than pure SAPO-34. The small mean pore diameter of composite could be mainly responsible for its pore blockage and higher deactivation rate. Meanwhile, since the SAPO-34 prepared by dry-gel method had inherently high mesoporosity, the AlMCM-41 introduction did not promote the molecular diffusion in the composite structure. The coke content was found 15.5% for deactivated composite smaller than that for the SAPO- 34 catalyst which could be due to the pore blockage and deactivation of the composite in a shorter period.

Insights into the doping effect of rare-earth metal on ZnAl2O4 supported PtSn catalyzed isobutane dehydrogenation

Isobutane dehydrogenation is a vital route for the production of isobutene, an important substance for methyl tert-butyl ether. However, the reaction is typically performed at relatively low pressure and high temperature, resulting in a facilitated coke formation. Here, we used rare-earth metals (Y, La, Ce) as dopants to modify the ZnAl2O4 support and studied their effects on Pt-Sn catalyzed dehydrogenation of isobutane. Combining the experimental and theoretical results, it is demonstrated that while Y and La tend to incorporate into the matrix of ZnAl2O4, separate CeO2 phase could be easily formed on ZnAl2O4 surface, leading to a decrease in both amount and strength of the Lewis acid sites. And for the La-ZnAl2O4, because of the large local deformation, oxygen vacancy can be readily formed, and results in a lot acid sites in the subsurface layer available for reactions. Deactivation rates of the catalysts in isobutane dehydrogenation is found to linearly correlate with the Lewis acid amounts over the modified supports. Compared with the catalysts of Pt-Sn/ZnAl2O4, Pt-Sn/La-ZnAl2O4 and Pt-Sn/Y-ZnAl2O4, Pt-Sn/Ce-ZnAl2O4 exhibits superior catalytic performance due to the low coke contents and high Pt dispersion. These results may provide additional insights on the design and optimization of isobutane dehydrogenation catalysts by tailoring the composition and structure of oxide supports.

Hierarchical ZSM‐5 Catalysts: The Effect of Different Intracrystalline Pore Dimensions on Catalyst Deactivation Behaviour in the MTO Reaction

AbstractAbstract: We present the effect of different combinations of intracrystalline pore systems in hierarchical ZSM‐5 zeolites on their performance as MTO catalysts. We prepared ZSM‐5 zeolites with additional intracrystalline mesoporous, intracrystalline macropores and a novel ZSM‐5 type zeolite with intracrystalline meso and macropores. The catalytic results showed that both used catalysts with mesopores and macropores exhibited three times longer catalyst lifetime compared to a conventional catalyst. However, TGA analysis of the deactivated catalysts showed much larger coke content in the mesoporous catalyst than in the macroporous catalyst. Consequently, macropores predominantly led to reduced coke formation rate while additional mesopores predominantly enhanced the resistance against deactivation by coke. Combining both intracrystalline meso and macropores in one catalyst lead to a tenfold increase in catalyst lifetime. Besides the effect on the catalyst lifetime there was also a strong effect of the additional pore systems on the selectivity of the catalysts. The catalysts containing mesopores showed reduced selectivity to short chain olefins and increased selectivity to larger hydrocarbons in comparison to the catalysts without a mesopores system.

The Effect of Co-feeding Methyl Acetate on the H-ZSM5 Catalysed Methanol-to-Hydrocarbons Reaction

The reactivity of methanol and methyl acetate mixtures over a HZSM-5 catalyst is studied over a period of 6 h at 350 °C, with small molecular weight olefins and aromatic compounds observed as reaction products. Post-reaction analysis of the catalyst shows the coke content to increase with methyl acetate content. Vibrational spectra (DRIFTS and inelastic neutron scattering, INS) indicate the major hydrocarbon species present in the coked catalysts to be methylated aromatic molecules, with INS spectra indicating a greater degree of methylation in the catalysts used with higher methyl acetate content. The greater extent of deactivation at higher methyl acetate concentrations is tentatively attributed to a diminishment of water in the zeolite cavity, which would otherwise facilitate re-generation of the active sites.

Long-time simulation of catalytic MTO reaction in a fluidized bed reactor with a coarse-grained discrete particle method — EMMS-DPM

Long-time behaviors widely exist in gas–solid reactors, e.g., the coke deposition and catalyst deactivation in the methanol to olefins (MTO) process. Due to the limitation of the computational cost, previous simulations of MTO reactors were mainly conducted with two-fluid model at short-time scales and assumed that the catalyst are perfectly mixed. Efficient simulation methods are, therefore, highly desirable, even for evaluating the assumptions through very long-time investigation. In this study, the MTO reaction kinetics is incorporated into a coarse-grained discrete particle method, namely EMMS-DPM, to simulate a pilot-scale reactor for 8 h of physical time. The simulation is validated by comparing the obtained gaseous products and coke contents with the experimental data. The perfect mixing assumption is validated by observing the residence time distribution of the catalyst for the whole reactor. The detailed coke content could provide more accurate data for accelerating steady state simulations. Furthermore, the relation between the coke content and age of the catalyst is directly obtained for the first time, which is valuable to effective use of the catalyst before discharging. The coke content is positively correlated to the age, but is also influenced by local conditions. For example, near the distributor, the catalyst particles are not well mixed and the maximum reaction rate fluctuates significantly even at large time scales. Thus, long-time particle-scale simulation would provide more dynamic details to characterize the reaction in the critical regions of the reactor, thus being very helpful to optimize operating conditions and the reactor designs.

Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts

Gas phase conversion of glycerol to acrolein over a variety of aluminum phosphate (AlP) catalysts synthesized by a simple replacement reaction method with a variation in calcination temperature (300-700 oC, AlP-300, AlP-400, AlP-500, AlP-600, and AlP-700, respectively) has been investigated. The textural properties, acidities and coke contents of the samples were also determined. The catalysts were presented in an amorphous state when the AlP sample was calcined below 500 oC. Further increasing the calcination temperature promoted the formation of orthorhombic α-AlPO4 crystal. The weak acid sites increased when the calcination temperature was raised from 300 to 500 oC. However, the weak acid sites decreased when the AlP was calcined above 500 oC. The acidity of the catalyst played a crucial role in the glycerol dehydration reaction. The maximum acrolein selectivity of 66% at 98% glycerol conversion was obtained over AlP-500 catalyst, due to the largest number of acid sites and appropriate textural properties. AlP-700 exhibited the lowest glycerol conversion, owing to the formation of orthorhombic α-AlPO4 crystalline phase and the lowest amount of acid sites under high calcination temperature. The significant reduction in the acidity of the used sample led to a decrease of glycerol conversion.

Kinetic Study of Selective Chlorination of Iron in Ilmenite Ore

The selective chlorination of ilmenite with coke and chlorine gas was conducted in the fixed bed reactor and effects of coke content and reaction temperature on reaction rate were investigated. In particular, the chlorination rate of iron in ilmenite was simulated by the unreacted shrinking core model. The reaction rate was simulated by calculating the chlorine gas consumption rate as the unreacted core shrinks. In addition, each of reaction resistances that chemical reaction at the reaction interface, diffusion through the product layer, and boundary film mass transfer resistances were calculated. The simulated reaction rates were in good agreement with the experimental results and the rate controlling step changed as the chlorination reaction progressed. Furthermore, the diffusion resistance through the product layer was dominant at lower reaction temperature, whereas the chemical reaction was dominant as the reaction temperature increased. It is because the diffusion of chlorine gas through the product layer could be hindered at lower reaction temperatures. Key words: Ilmenite, Selective chlorination, Synthetic rutile, Shrinking core model

Modeling of the catalytic cracking: Catalyst deactivation by coke and heavy metals

This paper proposes a model of the cracking process considering the catalyst deactivation by Ni, V and coke. The developed model is sensitive to the feedstock composition and describes the kinetics of cracking reactions leading to coke formation, the structural and selective properties of the catalyst. It also reflects the main technological parameters. The forecast calculations showed that when the resins and Ni contents in the feedstock increase by 4.2 wt% and 0.6 ppm, the coke contents on the catalyst increase by 0.75 and 0.32 wt% wt. under the other equal conditions. The catalyst activity decreases by 4.4% relative to initial value along with increasing the V content in the feedstock by 1.9 ppm due to its dealumination. If the Ni with V co-presence in the catalytic cracking feedstock and the Ni content increases by 0.6 ppm, the V destructive effect reduces by 1.2% due to reaction of Ni with the vanadic acid, also Ni on the catalyst increases the catalyst dehydrogenation activity. According to the calculations performed, the yield of the gasoline fraction changes by 4.43 wt%, depending on the feedstock composition (CSH/CAH = 1.6–1.8 units), other things being equal.

Catalytic activity of heteropoly tungstate catalysts for ethanol dehydration reaction: Deactivation and regeneration

The pure and palladium doped 12-tungstophosphoric acid - H3PW12O40 (HPW) and its cesium salts CsxH3-xPW12O40 (x = 1, 2, 2.25 and 2.5) were prepared and characterized by thermal analysis, FTIR, XRD, BET and XPS methods. In this paper were determined the optimal reaction temperature and the effect of palladium on the coke content during the dehydration of ethanol in the temperature range of 200−350 °C. Above 300 °C, a strong deactivation of the catalysts was caused by coke formation. The catalytic tests demonstrate that by supporting the HPW and PdyPW (y = 0.15, 0.2 and 0.25) on mesoporous molecular sieve SBA-15 the catalytic activity in ethanol dehydration reaction was improved. Palladium doping of HPW/SBA-15 significantly decreases the formation of coke deposit. The formation of coke during the ethanol dehydration does not affect the Keggin structure which led us to conclude that such catalysts can be regenerated in air and regain their catalytic activity for a short time.

Flame front progress in gas assisted iron ore sintering

The present paper is focused on the control of heat release and on the propagation of the flame front in an iron ore sinter bed. Small scale sinter experiments are performed in cylindrical packings of the sinter mix which are ignited at the bed surface and vertically passed by the suction gas. The heat front propagation is found to be closely linked to the consumption of the fuel mix in the sinter bed. Based on this findings, a dual fuel approach is explored whereas front propagation of the solid fuel combustion (coke breeze) is supported by pulsed injection of a secondary gaseous fuel. A non-stationary, one dimensional model is established to analyse the heat wave travelling in the sinter bed. The model setup describes a local thermal non-equilibrium between the sinter bed being defined as porous medium and the permeating gas. The model is based on the balance equations for the mass and heat transports caused by the solid and gaseous fuel combustion. Model calculations support the experimental findings and demonstrate that satisfying sinter peak temperature levels and locally focused energy release are ensured by combined solid fuel burnout and high temperature gas combustion. During some lab-scale sintering tests, coke breeze content was reduced in the sinter feed mixture, and secondary fuel gas was supplied in pulsed mode to compensate the missing energy demand. The flame front speed as well as properties related to the sinter quality such as the tumble and shatter strength were determined, with the later index showing more sensitive results. The investigations demonstrate that pulsed methane injection can increase the flame front speed compared to the pure coke case with 5.1 wt% coke. , the pulsed gaseous fuel combustion can nearly compensate the strength loss for a moderately coke reduced rawmix with a coke content of 3.5 wt%.

The Effects of Coke Parameters and Circulating Flue Gas Characteristics on NOx Emission during Flue Gas Recirculation Sintering Process

The new process of flue gas recirculation, which reduces coke consumption and reducing NOx emissions, is now extensively used. Compared with traditional sintering, the characteristics of circulating flue gas and coke parameters significantly affect the combustion atmosphere and coke combustion efficiency. Based on the actual complex process of sintering machine, this study proposes a relatively comprehensive one-dimensional, unsteady mathematical model for flue gas recirculation research. The model encompasses NOx pollutant generation and reduction, as well as SO2 generation and adsorption. We focus on the effects of cyclic flue gas characteristics on the sintering-bed temperature and NOx emissions, which are rarely studied, and provide a theoretical basis for NOx emission reduction. Simulation results show that during sintering, the fuel NOx is reduced by 50% and 10% when passing through the surface of coke particles and CO, respectively. During flue gas recirculation sintering, the increase in circulating gas O2 content, temperature, and supply-gas volume cause increased combustion efficiency of coke, reducing atmosphere, and NOx content in the circulating area; the temperature of the material layer also increases significantly and the sintering endpoint advances. During cyclic sintering, the small coke size and increased coke content increase the char-N release rate while promoting sufficient contact of NOx with the coke surface. Consequently, the NOx reduction rate increases. Compared with the conventional sintering, the designed flue gas recirculation condition saves 3.75% of coke consumption, i.e., for 1.2 kg of solid fuel per ton of sinter, the amount of flue gas treatment is reduced by 21.64% and NOx emissions is reduced by 23.59%. Moreover, without changing the existing sintering equipment, sintering capacity increases by about 5.56%.