Applied Fundamental Study On Coker Gas Oil Catalytic Pyrolysis And Coker Naphtha Upgrading Based On TMP Technology

Fluid Catalytic Cracking (FCC) is playing an increasingly important role in the refining-chemical industry since 21st centrury. Petroleum resource all over the world is more inferior and heavier, which results in productivity of delayed coking increasing unceasingly. Coker Gas Oil (CGO) becomes an important way of expanding the sources of the raw feedstock and reducing the processing cost for catalytic cracking unit. Using CGO as catalytic pyrolysis feedstock to produce petrochemicals is an efficient route with great potential. However, a large amount of aromatics and basic nitrogen compounds present in CGO that can poison FCC catalysts, which is adverse to CGO FCC processing. Study on the basic poisoning rules of FCC catalysts in high basic nitrogen compounds environment, regeneration behavior and the catalytic cracking performance of CGO becomes quite necessary.In this study, using pyridine and quinoline as model basic nitrogen compounds, the poisoning rules of them to different catalysts were investigated on the FCC pilot scale unit firstly. Results showed that, conversions, products distribution, selectivity of olefins and iso-hydrocarbons were all affected on different catalysts in varying degrees with model basic nitrogen compounds being introduced in. In general, ZSM-5 zeolite was affected more seriously than USY zeolite. Pyridine which was monocyclic had almost no contribution to the yield of coke while polyaromatic basic nitrogen compounds apt to coke much which could attribute to the density of electron cloud of basic nitrogen compounds.Molecular simulation and calculation by computer was used to simulate the adsorption and diffusion behavior of model basic nitrogen compounds molecular on different zeolite. Results showed that, there were some differences in adsorption quantity between them on the same zeolite. In addition,the coke reason of macromolecule basic nitrogen compounds was calculated and deduced.The extraction of basic nitrogen compounds from CGO was characterized by EIS-FT-TCR-MS and FI-IR spectra accurately. Results showed that the structure of the extraction was most likely naphthenoquinoline with side chain. Inorganic acid solution extracted of basic nitrogen compounds effectively, which attributed to the high solution of acid. EIS-FT-TCR-MS results showed that basic nitrogen compounds in CGO were mainly for the N1 class with carbon number locating between 22-28 and DBE locating between 9-12. Generally speaking, basic nitrogen compounds extracted from CGO represented the main species of basic nitrogen compounds in CGO, which was mainly quinoline-derives with three rings.Basic nitrogen compounds in CGO were extracted and it was found that their poisons effect on catalyst was similar to model basic nitrogen compounds. Macromolecules basic nitrogen compounds can crack into micro-molecule after adsorbing onto the acid site. And quite a few part of basic nitrogen condense to form coke.Catalysts before and after nitrogen-containing materials and basic nitrogen extraction coked were characterized by NH3-TPD and infrared spectrometry (FT-IR). At the same time, regeneration behavior of coked catalyst with nitrogen compounds deposit on it was investigated. NH3-TPD spectrometry showed that most of the strongly acid sites had been deactivated and poisonous effect by complex macromolecular basic nitrogen compounds was more serious than micro molecules basic nitrogen compounds on the same catalyst. While comparing the two kinds of catalyst, LTB-2 was affected less than LVR-60R. FT-IR spectrometry showed that there was no essential difference between the coke produced by nitrogen-containing feedstock and common coke produced by low nitrogen-containing feedstock. But introduction of macromolecules basic nitrogen compounds played an important role in the coke formation process. Typical coked catalysts were characterized by TG-MS.MS data showed that the first step of nitrogen in coke oxidation was opening of N-containing heterocyclic ring which generate HCN, and then being oxide to be NO. The temperature of NO peak was higher than CO2 which indicates that there was precedence order between C and N oxidation. So it was necessary to improve regeneration temperature to recover the catalytic activity of catalyst in catalytic cracking unit when high nitrogen feedstock was processed.Using the thermal gravity data of different coked catalyst, simple kinetics calculation was implemented. Results showed that apparent activation energy obtained by calculation was on the low side. But for the same kind of catalyst, apparent activation energy of nitrogen-containing coked catalyst had no significant difference with ordinary coked catalyst. Catalyst with higher coke content had a higher apparent activation energy which indicated that coke regeneration apparent activation energy of catalyst had direct relationship with coke content.Catalytic pyrolysis performance of CGO was investigated on Fluid Catalytic Cracking Pilot Scale Unit. Results showed that TMP process had good adaptability on CGO. While operating under atmosphere pressure, products distribution was good. Even under the industrial pressure, yield of LPG and propylene also reaches up to 30.24 wt% and 18.19wt % respectively. In addition, combination of CGO catalytic pyrolysis and delayed coker naphtha upgrading was investigated. Result indicated that it was not very suitable for delayed coking upgrading naphtha alone in riser. But the gasoline octane number could reach up to 90 when delayed coker naphtha was upgraded combination with CGO catalytic pyrolysis with the ratio of 25wt%, which could improve properties of gasoline effectively.