Nitrocellulose (flash paper) synthesis without Sulfuric Acid? According to the Wikipedia page on Nitrocellulose:  


  The process uses nitric acid to convert cellulose into cellulose nitrate and water:
  $$\ce{3HNO3 + C6H10O5 -&gt;[H2SO4] C6H7(NO2)3O5 + 3H2O}$$ 
  The sulfuric acid is present as a catalyst to produce the nitronium ion, $\ce{NO2+}$. The reaction is first order and proceeds by electrophilic substitution at the C−OH centers of the cellulose.[8]  


Since I have been on quarantine, I have lost access to the lab and therefore must carry out reactions from the comforts of my home. I have some sulfuric acid drain cleaner that is sufficient for many at-home applications. However, it consists of only about 93% $\ce{H2SO4}$, and contains a lot of dark dyes. I am trying to synthesize nitrocellulose paper from letter printer paper and envelopes, for the purpose of developing a self-destructing letter that burns away when the letter is returned to the envelope after being removed. However, the dyes in the sulfuric acid severely discolor the paper, and make it stand out considerably in a pile of mail, defeating the purpose of secrecy. So, at least until the quarantine is lifted, I may need an alternative catalyst to Sulfuric acid to synthesize the nitronium ions in vitro. Does anyone have an alternative to $\ce{H2SO4}$, or a way to eliminate the dyes without distillation? (because I broke my condenser column, and can't use the lab's)

Update: I'm still curious about my question, but it might not even be legal to send nitrocellulose envelopes through the mail. One spark and you could end up with flaming mail processing machines. Yikes!
I do not think it will be possible to form nitrate esters of cellulose without sulfuric acid present, I am sure that you need the strong bronsted acid to make the reaction work. But I think that there is another issue here, your safety / health / the law on energetic materials.

I hate to have to say this, but I do not think it is safe to make energetic materials using nitric acid at home. You should also consider for a moment the question of "is it legal" to make the energetic material at home.

Keep in mind years ago some "home chemists" would make explosives / fireworks and it was regarded as "boys will be boys". But nowadays the "boys in blue" (Police) are very keen to chase after people who make explosives / things which go bang etc.

I think that the distillation of sulfuric acid at home does not sound like a good idea, I think that you would need to work in a good fume hood. Most school labs would be unlikely to have the equipment required to do it.

With all due respect I think you should choose another chemical project to pass the time while you are on "lockdown".