Is my catalytic converter the problem?

I have a Honda civic 91 and its a 4th gen sedan. The problem with it is that the engine cranks but it won't start. I checked the spark plugs and they are all good. Battery has been recently replaced. What i don't get is why it starts up at times and doesn't. Could it be by any chance the catalytic converter that's ruined?

Added (1). I checked it recently, it wants to start but it chokes.

Replacing the catalytic converter on a "whim" can be an expensive mistake. I would change the fuel filter first, then test the fuel pressure on the fuel rail pressure fitting. The dealer of the car will know what the fuel pressure should be.

Have you twisted an ignition wire boot off any of the spark plugs, stuck a factory recommended new plug in the boot, grounded the threads on the motor and has someone spin the starter motor to see if you had any spark?

You can remove the O2 sensor from the exhaust and try to start it, if it starts it could be the cat or a defective crushed exhaust pipe (internal dual wall pipe, the inside wall collapses and blocks the flow of exhaust gasses) or put a vacuum gauge and watch it while cranking it over, it there's a blockage the gauge will fist show a vacuum than it will return to zero.

If the cat converter was bad enough to prevent starting, it wouldn't be intermittent. Get back to the basics; check for spark while cranking, check fuel pressure, check to see if the fuel injector is firing.

Cat converts don't go bad for a while and then go good so look somewhere else.

Check for a lose venturi just inside the carburetor.Tighten it up if loose.

There's no reason to suspect the cat anymore than loads of other components

Have you checked the distributor cap? Could have oil

Anyone that thinks a cat converter will keep the motor from starting should close the hood and get a mechanic! You are not even close to understanding how a motor works and are dangerous under the hood!