Temperature-programmed reaction techniques and Raman spectroscopy were used to characterize coke species deposited on a 5% Ni/MgAl 2 O 4 catalyst for dry reforming of methane. The CH 4 temperature-programmed decomposition profiles showed that the ignited decomposition temperatures of CH 4 increased from 273 to 378 °C when …
DetailsCoke deposited on catalytic cracking catalysts has been investigated by continuously monitoring evolved CO and CO2 during temperature-programmed oxidation (TPO) in a 1% O2/N2 mixture. Analyses were carried out on spent samples recovered from an industrial catalytic cracker and on coke prepared in the laboratory by exposure of …
DetailsIn industrial catalytic processes, coke deposition can cause catalyst deactivation by covering acid sites and/or blocking pores. The regeneration of deactivated catalysts, thereby removing the coke and simultaneously restoring the catalytic activity, is highly …
DetailsThe coke deposited on the catalyst can be removed via steam-gasification for syngas production . During steam gasification of coked catalyst, the heteroatoms components are converted to SO x and NO x, this emission is within the reservoir, minimizing environmental footprints. The coke-steam gasification reaction is catalysed …
DetailsConsequently, in order to obtain results corresponding to the coke deposited on catalyst particles, so that this coke can be directly related to the activity loss, the TPH and TPO results shown in Fig. 11 (a and b), respectively, correspond to samples of deactivated catalyst particles with uniform size (in the 150–300 μm range, which is that ...
DetailsThe nature and composition of the coke deposited on Pt–Pd catalysts supported on acid carriers during the hydroprocessing (hydrocracking and hydrotreating) of light-cycle oil (LCO) has been studied. Five types of supports have been used: a commercial cracking catalyst, alumina, Hβ zeolite, and two HY zeolites (with different …
DetailsCoke formation is the prime cause of catalyst deactivation, where undesired carbon wastes block the catalyst surface and hinder further reaction in a broad gamut of industrial …
DetailsThis process always employs acidic zeolite catalysts on which coke formation now represents arguably the major concern for reaction deactivation. ... a MTH reaction, the coke volume had exceeded the concomitant decrease in void volume; therefore, there must have been coke deposited over the external zeolite surfaces. …
DetailsExercise 6 - Material Balance for FCC Regenerator Problem Burning the coke deposited on the catalyst particles generates all the heat necessary for catalytic cracking. Therefore, the coke burning rate is a critical parameter to control the rate of cracking. The composition of dry flue gas from the regenerator of an FCC unit is given in vol% as ...
DetailsBurning the coke deposited on the catalyst particles generates all the heat necessary for catalytic cracking. Therefore, the coke burning rate is a critical parameter to control the rate of cracking. The composition of dry flue gas from the regenerator of an FCC unit is given in vol% as follows: Gas Volume % N2 81.6 CO2 15.7 CO 1.5 O2 1.2 The ...
DetailsThe coke deposited on the surfaces of Ni/HZSM-5 catalyst in bio-oil hydrodeoxygenation (HDO) was characterized by using a technique of X-ray photoelectron spectroscopy. The results show that the compounds with carbon related oxygen are the main constituent of the coke on the Ni/HZSM-5 catalysts. The amount of carbon …
DetailsAfter running for 215 days, the deactivated ZSM-5/ZSM-11 co-crystallized zeolite catalyst was regenerated in situ, i. e. burning the deposited coke at a GHSV of 1500 h − 1 under dilute oxygen in N 2 (O 2 1–5 vol.%) and temperatures of 450–550 °C. Subsequently, the regenerated catalyst proceeded with alkylation of benzene with FCC …
DetailsThis comprehensive study investigates the structural deposition of coke, particularly its association with sulphides, in spent hydrocracking and reforming catalysts, leveraging advanced kinetic modelling and characterization techniques. Its objective is to elucidate coke removal kinetics, offering insights into optimizing catalyst regeneration. …
DetailsKeywords: catalyst deactivation, soft X-ray absorption, Ni–W sulfide, zeolite 1. Introduction There have been lots of studies on the properties and structures of coke deposited on catalysts, because the coke deposition is a serious catalyst deactivation cause in many catalytic processes [1]. Typical techniques used for the
DetailsCoke deposition on hydrotreating catalysts is one of the main reasons of deactivation. In situ coke removal is advantageous compared to the off-site coke removal. This paper studies tetralin (THN) treatment of a deactivated industrial diesel hydrogenation Mo–Co–Ni/W–Al catalyst at conditions similar to the operation, 300–400 °C without H2. …
DetailsCeria dispersed on α-alumina, used as a model catalyst for coke oxidation, allows coke oxidation at lower temperatures. Using these catalysts, coke deposited in situ is shown …
DetailsThe speciation of coke on FCC catalyst is spatially heterogeneous. • Coke species are both physically deposited and chemically adsorbed on acid sites. • Upon the rapid heat-up, …
DetailsTemperature-programmed oxidation (TPO), Raman spectrometry, and X-ray photoelectron spectroscopy (XPS) are used to characterize coke species deposited on a 0.61wt% Pt/alumina catalyst for three ...
DetailsCoke deposition on spent noble metal catalysts used in petroleum/petrochemical industries is of serious concern on account of its impact on the catalyst deactivation and consequent loss in the production yield. In order to counteract the effects of coke deposition, it is vital to know the location as well as the nature and …
DetailsIt follows from (5) and (6) that both Eqs.(4) formally correspond to an increase in the coke concentration regardless of the level of catalyst activity, while the activity decreases with C.In this case, coke is deposited either as a monolayer or in the form of an avalanche, that is, immediately as a thick layer [].Despite the simplicity, …
DetailsTemperature-programmed oxidation (TPO), Raman spectrometry, and X-ray photoelectron spectroscopy (XPS) are used to characterize coke species deposited on a 0.61 . wt% Pt/alumina catalyst for three reactions, carried out separately: partial oxidation (POX), steam reforming (SR), and autothermal reforming (ATR).. Three individual …
DetailsThe determination of the activation energy (E a) required for coke removal can be used to evaluate the coke deposited on the catalyst surface [23, 24], and the E a values are an indication of how easy the coke can be removed from the catalyst. The coke amount can be accurately measured by thermal treatment in oxidant atmosphere [25, 26].
DetailsOperando ultraviolet–visible light spectroscopy (Operando UV–vis) is used to characterize and observe the species of coke that deposited on the catalyst surface during reaction …
DetailsThe speciation of coke on FCC catalyst is spatially heterogeneous. • Coke species are both physically deposited and chemically adsorbed on acid sites. • Upon the rapid heat-up, aliphatic volatilised and graphatised on exterior surface. • The outward diffusion of light aliphatics is dominant for coke burn-off in air. •
DetailsThe characterization of coke deposited on spent catalysts for long-chain-paraffin (n-C 16–19) dehydrogenation has been investigated in this study. It can be concluded that the dehydrogenation operation conditions (such as TOS and temperature) affect the coke deposition on the catalysts. With the prolongation of the …
DetailsH2 treatment to the spent catalyst at 800 °C could effectively remove the internal coke of the catalyst, while the external coke with a graphite-like structure still kept stable. Methylated aromatics were considered coke precursors. ... The effects of internal coke (deposited in the zeolite micropores) and external coke (deposited on the outer ...
DetailsBi-ZSM-5 heteroatom zeolite catalyst is prepared by gas-solid isomorphous substitution for the catalysis of acetylene hydrochlorination with ZSM-5 as the parent zeolite and BiCl3 as the precursor.
DetailsThe coke precursors deposit on the catalysts do not block the pores of the catalysts, but deposited on the acid centres of catalyst. ... The coke on spent catalysts were studied by the ...
DetailsCoke characterization The amount of coke deposited on the catalyst has been measured by combustion of a sample taken from the fixed bed reactor. It should be noted that the coke deposited on the catalyst is subjected in the reactor to a stream of N2 of 5 L min−1 (at room conditions) at 500 C, which eliminates the volatiles that do not ...
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