RFCC catalysts

The product yield of LDPE and HDPE for the same degradation time is in the order of ZSM-5 catalyst > RFCC catalyst > thermal, and the cumulative yield of liquid product from LDPE was greater than that from HDPE. 

Generally speaking, resid FCC (RFCC) catalysts should be very effective in bottoms cracking, be metals tolerant, and coke and dry gas selective. Based on many years of fundamental research and industrial experiences, a series of RFCC catalysts, such as Orbit, DVR, and MLC, have been developed by the SINOPEC Research Institute of Petroleum Processing (RIPP) and successfully commercialized [1]. These catalysts are very effective in paraffinic residue cracking. However, in recent years more and more intermediate-based residue has been introduced into FCC units, and the performances of conventional RFCC catalysts are now unsatisfactory. Therefore, novel zeolites and matrices have been developed to formulate a new generation of RFCC catalysts with improved bottoms cracking activity and coke selectivity. 

The most widely used zeolite in petroleum refining so far is Y zeolite. Currently, REUSY zeolite is the main active component of RFCC catalysts. However, in the course of hydrothermal preparation of ultrastable Y zeolite, nonframework aluminum debris formed by dealumination could block the channels thus influencing the ion-exchange ratio of rare earth as well as the accessibility of active sites [2],... 

In China, most of the traditional RFCC catalysts (such as Orbit, DVR, and MFC mentioned above) are based on alnmina matrix, and the most widely used materials for alumina matrix preparation are alumina sol and modified active alumina [4]. Alumina matrix combines the virtnes of alumina-sol (better attrition resistance and coke selectivity) and active alnmina (higher cracking activity), thus improving the cracking activity and selectivity of the catalysts. However, the coke selectivity of the alumina matrix is nnsatisfactory when processing resid feed due to the insufficient amount of meso/macropores and higher concentration of acid sites. 

To improve bottoms cracking activity and coke selectivity of RFCC catalysts, novel zeolites and matrices have been developed recently. Commercial results showed that both VRCC-1 catalyst containing SOY zeolite and RSC-2006 based on silica modified alumina matrix have demonstrated excellent bottoms cracking capability and... 

In summary, the quantity of soft coke seems to increase with the surface area in the small-pore range (zeolite and matrix), while the stripping rate is determined inversely by the accessibility of the catalyst sites and increases with larger and nonconstrained pore systems. We can conclude that for delta coke limited RFCC catalyst selection it will be essential to assess the diferences in all the factors contributing to commercial delta coke. 

The proper choice of a feed injection system, regenerator, and catalyst are some of the key aspects of successful RFCC operation. 

In this work, LDPE and HDPE were used as the waste plastics and ZSM-5 and RFCC were used as the waste catalyst. The effects reaction temperature and catalyst concentration on the production of liquid products were investigated in a semi-batch reactor. 

The plastic samples used in this study were palletized to a form of 2.8 3.2min in diameter. The molecular weights of LDPE and HDPE were 196,000 and 416,000, respectively. The waste catalysts used as a fine powder form. The ZSM-5 was used a petroleum refinement process and the RFCC was used in a naphtha cracking process. The BET surface area of ZSM-5 was 239.6 m /g, whose micropore and mesopore areas were 226.2 m /g and 13.4 m /g, respectively. For the RFCC, the BET surface area was 124.5 m /g, and micropore and mesopore areas were 85.6 m /g and 38.89 m /g, respectively. The experimental conditions applied are as follows the amount of reactant and catalyst are 125 g and 1.25-6.25 g, respectively. The flow rate of nitrogen stream is 40 cc/min, and the reaction temperature and heating rate are 300-500 C and 5 C/ min, respectively. Gas products were vented after cooling by condenser to -5 °C. Liquid products were collected in a reservoir over a period of... 

P. O Connor "RFCC Operating Regimes and Catalyst Selection",... 

RFCC [Residual Fluid Catalytic Cracking] A process for cracking residues from petroleum distillation. It uses an ultrastable zeolite catalyst with two-stage regeneration. Originally developed in the early 1980s by Total Petroleum in Kansas and Oklahoma under the name R2R. Further developed by IFP with Stone and Webster and now more commonly known as RFCC. Twenty-six units had been licensed by 2003. 

Resid hydrotreating catalysts, developed in 1987 have been used together with a scale-and iron-removing catalyst for (1) the cracking and desulfurization of atmospheric residue, (2) the pretreatment of RFCC and (3) the cracking of vacuum residue. Approximately 7000 tons of industrial catalysts have been used in commercial units so far. 

There are some very clear differences in the operation and catalyst requirements of various commercial Resid FCC (RFCC) units. In this paper, the differences between activity-limited and delta-coke-limited RFCC operations are elucidated and the related catalyst performance requirements and catalyst selection methods are discussed. The effect of the catalyst-to-oil ratio on conversion and on catalyst site utilization and poisoning plays a key role in the transition of an RFCC unit from a catalyst-activity-limited regime to a cat-to-oil-limited regime. 

Clearly, improvements in FCC catalyst metal resistance and activity retention and in coke selectivity will allow the refiner to increase (bottoms) conversion and increase the intake of lower-valued residual feedstocks. On the other hand, the RFCC operating constraints will in general have a bigger impact on the profitability of the unit than incremental yield improvements. 

Clearly the last option mentioned is the most controversial one, as it implies that an optimum catalyst activity can be found which maximizes the conversion of a certmn operation. Indeed we have experienced several RFCC operations where this appears to be the case. 

A second factor which needs to be considered is the fact that in practice catalyst activity in RFCC is often boosted by increasing the zeolite activity and/or stability (metal traps). While the additional zeolite sites will contribute to more VGO cracking activity and an increased delta coke, they may not do that much as far as cracking the large hydrocarbon molecules is concerned. In fact an increase in zeolite activity because of the higher delta coke, and hence lower CTO, may result in a drop in the concentration of accessible "matrix" sites ... 

CATALYST SELECTION FOR DELTA-COKE-LIMITED RFCC 5.1. Types of delta coke... 

At present, the aforementioned patent techniques have been industrialized for preparation of Si-rich zeolites. The industrial equipment based on the CHZ-3 residual oil cracking catalyst prepared using the corresponding zeolite as the active component has been in operation for heavy-oil catalytic cracking (RFCC). 

From the operation results of the RFCC industrial apparatus it is seen that in comparison with the commonly used residual oil cracking catalyst CHZ-2, the CHZ-3 catalyst with the Si-rich zeolite as the active component increases the content of low-pressure residual oil by 8.02%, whereas it decreases the oil pulp yield by 1.34% under circumstances where the coke yield remains constant. Meanwhile, the light-oil component yield increases by 1.10%, whereas the combined yeild of liquefied gas + light oil increases by 1.73% if CHZ-3 catalyst is used, indicating that this catalyst has excellent activity-stability as well. 

The importance of diffusion restrictions in FCC catalysis is often questioned. Short-contact-time pilot riser experiments confirm that combining zeolites with diffusion-enhancing matrices can result in significant product selectivity and product property improvements. The industrial benefits of a nonzeolite matrix on bottoms cracking in heavy vacuum gas oil (VGO) and resid FCC (RFCC) have also been confirmed in practice. Recently, some new methods have been used to measure the accessibility of FCC catalysts. 

With the advent of better catalysts and effective additives, FCC feed preparation by vacuum distillation has become redundant for certain low-metal/CCR crude oils, so that the atmospheric residue can be processed in an FCC unit directly. The range of crude oils from which the atmospheric residue can be processed directly can be extended by revamping existing FCC units or building special new FCC units, RFCC units, and/or heavy-oil crackers. 

The main feature of such an RFCC revamp is increasing the coke-burning capacity of the regenerator while maintaining the FCC unit in heat balance (often by incorporating catalyst coolers in the regenerator). Also, the employment of improved catalysts that reduce coke formation and enhance tolerance for metals (notably V, Fe, and Na) has enabled this development in RFCC. 

RFCC (resid fluid catalytic cracking) is one of the processes for the conversion of heavy oils in modem refineries. The problem with vacuum residue as FCC feedstock is quick deactivation of catalysts by the coking of asphaltene fractions and the deposition of metals involved in metallorganic polycyclic compounds. Therefore, developing novel zeolites to achieve metal tolerance has long been a goal of catalyst researchers... 

Moreover, the structure destruction of EAH-USY by metals was found to be related to the valence state of the metal ions. As shown in Figure 8, the higher the valence of metal ions, the more serious the structural effect of these metals. This might be explained either by the repulsive force between metal ions or the difficulty of diffusion of low valence metal ions in zeolite inner chaimels due to their large radius. In commercial RFCC units, it is useful to alleviate metal contamination by controlling the excess oxygen concentration in regenerator in order to keep the metals deposited on catalysts in a low valence state. 

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